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x*(x-3)*x+4*x-7=0 equation

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Numerical solution:

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The solution

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x*(x - 3)*x + 4*x - 7 = 0
$$\left(x x \left(x - 3\right) + 4 x\right) - 7 = 0$$
The graph
Rapid solution [src]
              ______________                             /             ______________                        \
             /       ______                              |            /       ______                         |
            /  5   \/ 2037                               |    ___    /  5   \/ 2037                          |
         3 /   - + --------                              |  \/ 3 *3 /   - + --------              ___        |
         \/    2      18                 1               |        \/    2      18               \/ 3         |
x1 = 1 - ------------------- + --------------------- + I*|- ------------------------- - ---------------------|
                  2                   ______________     |              2                      ______________|
                                     /       ______      |                                    /       ______ |
                                    /  5   \/ 2037       |                                   /  5   \/ 2037  |
                               6*3 /   - + --------      |                              6*3 /   - + -------- |
                                 \/    2      18         \                                \/    2      18    /
$$x_{1} = - \frac{\sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2} + \frac{1}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}} + 1 + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2} - \frac{\sqrt{3}}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}\right)$$
              ______________                             /           ______________                        \
             /       ______                              |          /       ______                         |
            /  5   \/ 2037                               |  ___    /  5   \/ 2037                          |
         3 /   - + --------                              |\/ 3 *3 /   - + --------              ___        |
         \/    2      18                 1               |      \/    2      18               \/ 3         |
x2 = 1 - ------------------- + --------------------- + I*|------------------------- + ---------------------|
                  2                   ______________     |            2                      ______________|
                                     /       ______      |                                  /       ______ |
                                    /  5   \/ 2037       |                                 /  5   \/ 2037  |
                               6*3 /   - + --------      |                            6*3 /   - + -------- |
                                 \/    2      18         \                              \/    2      18    /
$$x_{2} = - \frac{\sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2} + \frac{1}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}} + 1 + i \left(\frac{\sqrt{3}}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}} + \frac{\sqrt{3} \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2}\right)$$
              ______________                        
             /       ______                         
            /  5   \/ 2037               1          
x3 = 1 + 3 /   - + --------  - ---------------------
         \/    2      18              ______________
                                     /       ______ 
                                    /  5   \/ 2037  
                               3*3 /   - + -------- 
                                 \/    2      18    
$$x_{3} = - \frac{1}{3 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}} + 1 + \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}$$
x3 = -1/(3*(5/2 + sqrt(2037)/18)^(1/3)) + 1 + (5/2 + sqrt(2037)/18)^(1/3)
Sum and product of roots [src]
sum
         ______________                             /             ______________                        \            ______________                             /           ______________                        \                                                  
        /       ______                              |            /       ______                         |           /       ______                              |          /       ______                         |                                                  
       /  5   \/ 2037                               |    ___    /  5   \/ 2037                          |          /  5   \/ 2037                               |  ___    /  5   \/ 2037                          |            ______________                        
    3 /   - + --------                              |  \/ 3 *3 /   - + --------              ___        |       3 /   - + --------                              |\/ 3 *3 /   - + --------              ___        |           /       ______                         
    \/    2      18                 1               |        \/    2      18               \/ 3         |       \/    2      18                 1               |      \/    2      18               \/ 3         |          /  5   \/ 2037               1          
1 - ------------------- + --------------------- + I*|- ------------------------- - ---------------------| + 1 - ------------------- + --------------------- + I*|------------------------- + ---------------------| + 1 + 3 /   - + --------  - ---------------------
             2                   ______________     |              2                      ______________|                2                   ______________     |            2                      ______________|       \/    2      18              ______________
                                /       ______      |                                    /       ______ |                                   /       ______      |                                  /       ______ |                                   /       ______ 
                               /  5   \/ 2037       |                                   /  5   \/ 2037  |                                  /  5   \/ 2037       |                                 /  5   \/ 2037  |                                  /  5   \/ 2037  
                          6*3 /   - + --------      |                              6*3 /   - + -------- |                             6*3 /   - + --------      |                            6*3 /   - + -------- |                             3*3 /   - + -------- 
                            \/    2      18         \                                \/    2      18    /                               \/    2      18         \                              \/    2      18    /                               \/    2      18    
$$\left(- \frac{1}{3 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}} + 1 + \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}\right) + \left(\left(- \frac{\sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2} + \frac{1}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}} + 1 + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2} - \frac{\sqrt{3}}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}\right)\right) + \left(- \frac{\sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2} + \frac{1}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}} + 1 + i \left(\frac{\sqrt{3}}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}} + \frac{\sqrt{3} \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2}\right)\right)\right)$$
=
      /           ______________                        \     /             ______________                        \
      |          /       ______                         |     |            /       ______                         |
      |  ___    /  5   \/ 2037                          |     |    ___    /  5   \/ 2037                          |
      |\/ 3 *3 /   - + --------              ___        |     |  \/ 3 *3 /   - + --------              ___        |
      |      \/    2      18               \/ 3         |     |        \/    2      18               \/ 3         |
3 + I*|------------------------- + ---------------------| + I*|- ------------------------- - ---------------------|
      |            2                      ______________|     |              2                      ______________|
      |                                  /       ______ |     |                                    /       ______ |
      |                                 /  5   \/ 2037  |     |                                   /  5   \/ 2037  |
      |                            6*3 /   - + -------- |     |                              6*3 /   - + -------- |
      \                              \/    2      18    /     \                                \/    2      18    /
$$3 + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2} - \frac{\sqrt{3}}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}\right) + i \left(\frac{\sqrt{3}}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}} + \frac{\sqrt{3} \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2}\right)$$
product
/         ______________                             /             ______________                        \\ /         ______________                             /           ______________                        \\                                                  
|        /       ______                              |            /       ______                         || |        /       ______                              |          /       ______                         ||                                                  
|       /  5   \/ 2037                               |    ___    /  5   \/ 2037                          || |       /  5   \/ 2037                               |  ___    /  5   \/ 2037                          || /         ______________                        \
|    3 /   - + --------                              |  \/ 3 *3 /   - + --------              ___        || |    3 /   - + --------                              |\/ 3 *3 /   - + --------              ___        || |        /       ______                         |
|    \/    2      18                 1               |        \/    2      18               \/ 3         || |    \/    2      18                 1               |      \/    2      18               \/ 3         || |       /  5   \/ 2037               1          |
|1 - ------------------- + --------------------- + I*|- ------------------------- - ---------------------||*|1 - ------------------- + --------------------- + I*|------------------------- + ---------------------||*|1 + 3 /   - + --------  - ---------------------|
|             2                   ______________     |              2                      ______________|| |             2                   ______________     |            2                      ______________|| |    \/    2      18              ______________|
|                                /       ______      |                                    /       ______ || |                                /       ______      |                                  /       ______ || |                                /       ______ |
|                               /  5   \/ 2037       |                                   /  5   \/ 2037  || |                               /  5   \/ 2037       |                                 /  5   \/ 2037  || |                               /  5   \/ 2037  |
|                          6*3 /   - + --------      |                              6*3 /   - + -------- || |                          6*3 /   - + --------      |                            6*3 /   - + -------- || |                          3*3 /   - + -------- |
\                            \/    2      18         \                                \/    2      18    // \                            \/    2      18         \                              \/    2      18    // \                            \/    2      18    /
$$\left(- \frac{\sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2} + \frac{1}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}} + 1 + i \left(\frac{\sqrt{3}}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}} + \frac{\sqrt{3} \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2}\right)\right) \left(- \frac{\sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2} + \frac{1}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}} + 1 + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}{2} - \frac{\sqrt{3}}{6 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}}\right)\right) \left(- \frac{1}{3 \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}} + 1 + \sqrt[3]{\frac{5}{2} + \frac{\sqrt{2037}}{18}}\right)$$
=
          ___________________                               2/3              __________________               ___________________                             2/3                    __________________                                      2/3                                         2/3
       3 /            ______        3 ___ /          ______\          2/3 3 /           ______      ______ 3 /            ______        3 ____ /       ______\       2/3   ______ 3 /           ______      3 ___   ______ /          ______\         3 ___ 6 ___   _____ /       ______\   
    15*\/  540 + 12*\/ 2037     225*\/ 2 *\135 + 3*\/ 2037 /      15*2   *\/  135 + 3*\/ 2037     \/ 2037 *\/  540 + 12*\/ 2037     225*\/ 18 *\45 + \/ 2037 /      2   *\/ 2037 *\/  135 + 3*\/ 2037     5*\/ 2 *\/ 2037 *\135 + 3*\/ 2037 /      15*\/ 2 *\/ 3 *\/ 679 *\45 + \/ 2037 /   
7 + ------------------------- - ------------------------------- - ----------------------------- - ------------------------------- + ----------------------------- + ----------------------------------- + -------------------------------------- - -----------------------------------------
                16                             32                               16                               48                               32                                 48                                     32                                         32                   
$$- \frac{15 \sqrt[3]{2} \sqrt[6]{3} \sqrt{679} \left(45 + \sqrt{2037}\right)^{\frac{2}{3}}}{32} - \frac{225 \sqrt[3]{2} \left(135 + 3 \sqrt{2037}\right)^{\frac{2}{3}}}{32} - \frac{\sqrt{2037} \sqrt[3]{540 + 12 \sqrt{2037}}}{48} - \frac{15 \cdot 2^{\frac{2}{3}} \sqrt[3]{135 + 3 \sqrt{2037}}}{16} + 7 + \frac{15 \sqrt[3]{540 + 12 \sqrt{2037}}}{16} + \frac{2^{\frac{2}{3}} \sqrt{2037} \sqrt[3]{135 + 3 \sqrt{2037}}}{48} + \frac{225 \sqrt[3]{18} \left(45 + \sqrt{2037}\right)^{\frac{2}{3}}}{32} + \frac{5 \sqrt[3]{2} \sqrt{2037} \left(135 + 3 \sqrt{2037}\right)^{\frac{2}{3}}}{32}$$
7 + 15*(540 + 12*sqrt(2037))^(1/3)/16 - 225*2^(1/3)*(135 + 3*sqrt(2037))^(2/3)/32 - 15*2^(2/3)*(135 + 3*sqrt(2037))^(1/3)/16 - sqrt(2037)*(540 + 12*sqrt(2037))^(1/3)/48 + 225*18^(1/3)*(45 + sqrt(2037))^(2/3)/32 + 2^(2/3)*sqrt(2037)*(135 + 3*sqrt(2037))^(1/3)/48 + 5*2^(1/3)*sqrt(2037)*(135 + 3*sqrt(2037))^(2/3)/32 - 15*2^(1/3)*3^(1/6)*sqrt(679)*(45 + sqrt(2037))^(2/3)/32
Numerical answer [src]
x1 = 2.51598022769282
x2 = 0.24200988615359 - 1.65034755068945*i
x3 = 0.24200988615359 + 1.65034755068945*i
x3 = 0.24200988615359 + 1.65034755068945*i