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-x^(5)+8*x^(4)-22*x^(3)+28*x^(2)-24*x+16=0 equation

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Numerical solution:

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The solution

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   5      4       3       2                
- x  + 8*x  - 22*x  + 28*x  - 24*x + 16 = 0
$$\left(- 24 x + \left(28 x^{2} + \left(- 22 x^{3} + \left(- x^{5} + 8 x^{4}\right)\right)\right)\right) + 16 = 0$$
The graph
Sum and product of roots [src]
sum
                                       ________________     /             ________________                          \                                      ________________     /           ________________                          \                                                      
                                      /          _____      |            /          _____                           |                                     /          _____      |          /          _____                           |                                                      
                                     /  82   2*\/ 159       |    ___    /  82   2*\/ 159                            |                                    /  82   2*\/ 159       |  ___    /  82   2*\/ 159                            |            ________________                          
                                  3 /   -- + ---------      |  \/ 3 *3 /   -- + ---------                ___        |                                 3 /   -- + ---------      |\/ 3 *3 /   -- + ---------                ___        |           /          _____                           
    4              5              \/    27       9          |        \/    27       9                5*\/ 3         |   4              5              \/    27       9          |      \/    27       9                5*\/ 3         |   4      /  82   2*\/ 159                10          
2 + - - ----------------------- - --------------------- + I*|- --------------------------- + -----------------------| + - - ----------------------- - --------------------- + I*|--------------------------- - -----------------------| + - + 3 /   -- + ---------  + -----------------------
    3          ________________             2               |               2                       ________________|   3          ________________             2               |             2                       ________________|   3   \/    27       9               ________________
              /          _____                              |                                      /          _____ |             /          _____                              |                                    /          _____ |                                     /          _____ 
             /  82   2*\/ 159                               |                                     /  82   2*\/ 159  |            /  82   2*\/ 159                               |                                   /  82   2*\/ 159  |                                    /  82   2*\/ 159  
        9*3 /   -- + ---------                              |                                9*3 /   -- + --------- |       9*3 /   -- + ---------                              |                              9*3 /   -- + --------- |                               9*3 /   -- + --------- 
          \/    27       9                                  \                                  \/    27       9     /         \/    27       9                                  \                                \/    27       9     /                                 \/    27       9     
$$\left(\frac{10}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}} + \frac{4}{3} + \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}\right) + \left(\left(2 + \left(- \frac{\sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2} - \frac{5}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}} + \frac{4}{3} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2} + \frac{5 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}\right)\right)\right) + \left(- \frac{\sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2} - \frac{5}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}} + \frac{4}{3} + i \left(- \frac{5 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}} + \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2}\right)\right)\right)$$
=
      /           ________________                          \     /             ________________                          \
      |          /          _____                           |     |            /          _____                           |
      |  ___    /  82   2*\/ 159                            |     |    ___    /  82   2*\/ 159                            |
      |\/ 3 *3 /   -- + ---------                ___        |     |  \/ 3 *3 /   -- + ---------                ___        |
      |      \/    27       9                5*\/ 3         |     |        \/    27       9                5*\/ 3         |
6 + I*|--------------------------- - -----------------------| + I*|- --------------------------- + -----------------------|
      |             2                       ________________|     |               2                       ________________|
      |                                    /          _____ |     |                                      /          _____ |
      |                                   /  82   2*\/ 159  |     |                                     /  82   2*\/ 159  |
      |                              9*3 /   -- + --------- |     |                                9*3 /   -- + --------- |
      \                                \/    27       9     /     \                                  \/    27       9     /
$$6 + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2} + \frac{5 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}\right) + i \left(- \frac{5 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}} + \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2}\right)$$
product
  /                                   ________________     /             ________________                          \\ /                                   ________________     /           ________________                          \\                                                      
  |                                  /          _____      |            /          _____                           || |                                  /          _____      |          /          _____                           ||                                                      
  |                                 /  82   2*\/ 159       |    ___    /  82   2*\/ 159                            || |                                 /  82   2*\/ 159       |  ___    /  82   2*\/ 159                            || /         ________________                          \
  |                              3 /   -- + ---------      |  \/ 3 *3 /   -- + ---------                ___        || |                              3 /   -- + ---------      |\/ 3 *3 /   -- + ---------                ___        || |        /          _____                           |
  |4              5              \/    27       9          |        \/    27       9                5*\/ 3         || |4              5              \/    27       9          |      \/    27       9                5*\/ 3         || |4      /  82   2*\/ 159                10          |
2*|- - ----------------------- - --------------------- + I*|- --------------------------- + -----------------------||*|- - ----------------------- - --------------------- + I*|--------------------------- - -----------------------||*|- + 3 /   -- + ---------  + -----------------------|
  |3          ________________             2               |               2                       ________________|| |3          ________________             2               |             2                       ________________|| |3   \/    27       9               ________________|
  |          /          _____                              |                                      /          _____ || |          /          _____                              |                                    /          _____ || |                                  /          _____ |
  |         /  82   2*\/ 159                               |                                     /  82   2*\/ 159  || |         /  82   2*\/ 159                               |                                   /  82   2*\/ 159  || |                                 /  82   2*\/ 159  |
  |    9*3 /   -- + ---------                              |                                9*3 /   -- + --------- || |    9*3 /   -- + ---------                              |                              9*3 /   -- + --------- || |                            9*3 /   -- + --------- |
  \      \/    27       9                                  \                                  \/    27       9     // \      \/    27       9                                  \                                \/    27       9     // \                              \/    27       9     /
$$\left(- \frac{\sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2} - \frac{5}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}} + \frac{4}{3} + i \left(- \frac{5 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}} + \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2}\right)\right) 2 \left(- \frac{\sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2} - \frac{5}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}} + \frac{4}{3} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2} + \frac{5 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}\right)\right) \left(\frac{10}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}} + \frac{4}{3} + \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}\right)$$
=
8
$$8$$
8
Rapid solution [src]
x1 = 2
$$x_{1} = 2$$
                                        ________________     /             ________________                          \
                                       /          _____      |            /          _____                           |
                                      /  82   2*\/ 159       |    ___    /  82   2*\/ 159                            |
                                   3 /   -- + ---------      |  \/ 3 *3 /   -- + ---------                ___        |
     4              5              \/    27       9          |        \/    27       9                5*\/ 3         |
x2 = - - ----------------------- - --------------------- + I*|- --------------------------- + -----------------------|
     3          ________________             2               |               2                       ________________|
               /          _____                              |                                      /          _____ |
              /  82   2*\/ 159                               |                                     /  82   2*\/ 159  |
         9*3 /   -- + ---------                              |                                9*3 /   -- + --------- |
           \/    27       9                                  \                                  \/    27       9     /
$$x_{2} = - \frac{\sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2} - \frac{5}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}} + \frac{4}{3} + i \left(- \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2} + \frac{5 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}\right)$$
                                        ________________     /           ________________                          \
                                       /          _____      |          /          _____                           |
                                      /  82   2*\/ 159       |  ___    /  82   2*\/ 159                            |
                                   3 /   -- + ---------      |\/ 3 *3 /   -- + ---------                ___        |
     4              5              \/    27       9          |      \/    27       9                5*\/ 3         |
x3 = - - ----------------------- - --------------------- + I*|--------------------------- - -----------------------|
     3          ________________             2               |             2                       ________________|
               /          _____                              |                                    /          _____ |
              /  82   2*\/ 159                               |                                   /  82   2*\/ 159  |
         9*3 /   -- + ---------                              |                              9*3 /   -- + --------- |
           \/    27       9                                  \                                \/    27       9     /
$$x_{3} = - \frac{\sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2} - \frac{5}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}} + \frac{4}{3} + i \left(- \frac{5 \sqrt{3}}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}} + \frac{\sqrt{3} \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}}{2}\right)$$
              ________________                          
             /          _____                           
     4      /  82   2*\/ 159                10          
x4 = - + 3 /   -- + ---------  + -----------------------
     3   \/    27       9               ________________
                                       /          _____ 
                                      /  82   2*\/ 159  
                                 9*3 /   -- + --------- 
                                   \/    27       9     
$$x_{4} = \frac{10}{9 \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}} + \frac{4}{3} + \sqrt[3]{\frac{2 \sqrt{159}}{9} + \frac{82}{27}}$$
x4 = 10/(9*(2*sqrt(159)/9 + 82/27)^(1/3)) + 4/3 + (2*sqrt(159)/9 + 82/27)^(1/3)
Numerical answer [src]
x1 = 3.75110070237603
x2 = 0.124449648811983 + 1.02511753217493*i
x3 = 0.124449648811983 - 1.02511753217493*i
x4 = 2.0
x4 = 2.0