Mister Exam

Other calculators

(x-7)^3=9(x+7) equation

The teacher will be very surprised to see your correct solution 😉

v

Numerical solution:

Do search numerical solution at [, ]

The solution

You have entered [src]
       3            
(x - 7)  = 9*(x + 7)
$$\left(x - 7\right)^{3} = 9 \left(x + 7\right)$$
The graph
Rapid solution [src]
                                    ________________     /           ________________                        \
                                 3 /          _____      |    ___ 3 /          _____               ___       |
                   3             \/  63 + 3*\/ 438       |  \/ 3 *\/  63 + 3*\/ 438            3*\/ 3        |
x1 = 7 - --------------------- - ------------------- + I*|- ------------------------- + ---------------------|
              ________________            2              |              2                    ________________|
           3 /          _____                            |                                3 /          _____ |
         2*\/  63 + 3*\/ 438                             \                              2*\/  63 + 3*\/ 438  /
$$x_{1} = - \frac{\sqrt[3]{3 \sqrt{438} + 63}}{2} - \frac{3}{2 \sqrt[3]{3 \sqrt{438} + 63}} + 7 + i \left(- \frac{\sqrt{3} \sqrt[3]{3 \sqrt{438} + 63}}{2} + \frac{3 \sqrt{3}}{2 \sqrt[3]{3 \sqrt{438} + 63}}\right)$$
                                    ________________     /         ________________                        \
                                 3 /          _____      |  ___ 3 /          _____               ___       |
                   3             \/  63 + 3*\/ 438       |\/ 3 *\/  63 + 3*\/ 438            3*\/ 3        |
x2 = 7 - --------------------- - ------------------- + I*|------------------------- - ---------------------|
              ________________            2              |            2                    ________________|
           3 /          _____                            |                              3 /          _____ |
         2*\/  63 + 3*\/ 438                             \                            2*\/  63 + 3*\/ 438  /
$$x_{2} = - \frac{\sqrt[3]{3 \sqrt{438} + 63}}{2} - \frac{3}{2 \sqrt[3]{3 \sqrt{438} + 63}} + 7 + i \left(- \frac{3 \sqrt{3}}{2 \sqrt[3]{3 \sqrt{438} + 63}} + \frac{\sqrt{3} \sqrt[3]{3 \sqrt{438} + 63}}{2}\right)$$
            ________________                      
         3 /          _____             3         
x3 = 7 + \/  63 + 3*\/ 438   + -------------------
                                  ________________
                               3 /          _____ 
                               \/  63 + 3*\/ 438  
$$x_{3} = \frac{3}{\sqrt[3]{3 \sqrt{438} + 63}} + \sqrt[3]{3 \sqrt{438} + 63} + 7$$
x3 = 3/(3*sqrt(438) + 63)^(1/3) + (3*sqrt(438) + 63)^(1/3) + 7
Sum and product of roots [src]
sum
                               ________________     /           ________________                        \                                  ________________     /         ________________                        \                                                
                            3 /          _____      |    ___ 3 /          _____               ___       |                               3 /          _____      |  ___ 3 /          _____               ___       |          ________________                      
              3             \/  63 + 3*\/ 438       |  \/ 3 *\/  63 + 3*\/ 438            3*\/ 3        |                 3             \/  63 + 3*\/ 438       |\/ 3 *\/  63 + 3*\/ 438            3*\/ 3        |       3 /          _____             3         
7 - --------------------- - ------------------- + I*|- ------------------------- + ---------------------| + 7 - --------------------- - ------------------- + I*|------------------------- - ---------------------| + 7 + \/  63 + 3*\/ 438   + -------------------
         ________________            2              |              2                    ________________|            ________________            2              |            2                    ________________|                                ________________
      3 /          _____                            |                                3 /          _____ |         3 /          _____                            |                              3 /          _____ |                             3 /          _____ 
    2*\/  63 + 3*\/ 438                             \                              2*\/  63 + 3*\/ 438  /       2*\/  63 + 3*\/ 438                             \                            2*\/  63 + 3*\/ 438  /                             \/  63 + 3*\/ 438  
$$\left(\frac{3}{\sqrt[3]{3 \sqrt{438} + 63}} + \sqrt[3]{3 \sqrt{438} + 63} + 7\right) + \left(\left(- \frac{\sqrt[3]{3 \sqrt{438} + 63}}{2} - \frac{3}{2 \sqrt[3]{3 \sqrt{438} + 63}} + 7 + i \left(- \frac{\sqrt{3} \sqrt[3]{3 \sqrt{438} + 63}}{2} + \frac{3 \sqrt{3}}{2 \sqrt[3]{3 \sqrt{438} + 63}}\right)\right) + \left(- \frac{\sqrt[3]{3 \sqrt{438} + 63}}{2} - \frac{3}{2 \sqrt[3]{3 \sqrt{438} + 63}} + 7 + i \left(- \frac{3 \sqrt{3}}{2 \sqrt[3]{3 \sqrt{438} + 63}} + \frac{\sqrt{3} \sqrt[3]{3 \sqrt{438} + 63}}{2}\right)\right)\right)$$
=
       /         ________________                        \     /           ________________                        \
       |  ___ 3 /          _____               ___       |     |    ___ 3 /          _____               ___       |
       |\/ 3 *\/  63 + 3*\/ 438            3*\/ 3        |     |  \/ 3 *\/  63 + 3*\/ 438            3*\/ 3        |
21 + I*|------------------------- - ---------------------| + I*|- ------------------------- + ---------------------|
       |            2                    ________________|     |              2                    ________________|
       |                              3 /          _____ |     |                                3 /          _____ |
       \                            2*\/  63 + 3*\/ 438  /     \                              2*\/  63 + 3*\/ 438  /
$$21 + i \left(- \frac{\sqrt{3} \sqrt[3]{3 \sqrt{438} + 63}}{2} + \frac{3 \sqrt{3}}{2 \sqrt[3]{3 \sqrt{438} + 63}}\right) + i \left(- \frac{3 \sqrt{3}}{2 \sqrt[3]{3 \sqrt{438} + 63}} + \frac{\sqrt{3} \sqrt[3]{3 \sqrt{438} + 63}}{2}\right)$$
product
/                               ________________     /           ________________                        \\ /                               ________________     /         ________________                        \\                                                
|                            3 /          _____      |    ___ 3 /          _____               ___       || |                            3 /          _____      |  ___ 3 /          _____               ___       || /       ________________                      \
|              3             \/  63 + 3*\/ 438       |  \/ 3 *\/  63 + 3*\/ 438            3*\/ 3        || |              3             \/  63 + 3*\/ 438       |\/ 3 *\/  63 + 3*\/ 438            3*\/ 3        || |    3 /          _____             3         |
|7 - --------------------- - ------------------- + I*|- ------------------------- + ---------------------||*|7 - --------------------- - ------------------- + I*|------------------------- - ---------------------||*|7 + \/  63 + 3*\/ 438   + -------------------|
|         ________________            2              |              2                    ________________|| |         ________________            2              |            2                    ________________|| |                             ________________|
|      3 /          _____                            |                                3 /          _____ || |      3 /          _____                            |                              3 /          _____ || |                          3 /          _____ |
\    2*\/  63 + 3*\/ 438                             \                              2*\/  63 + 3*\/ 438  // \    2*\/  63 + 3*\/ 438                             \                            2*\/  63 + 3*\/ 438  // \                          \/  63 + 3*\/ 438  /
$$\left(- \frac{\sqrt[3]{3 \sqrt{438} + 63}}{2} - \frac{3}{2 \sqrt[3]{3 \sqrt{438} + 63}} + 7 + i \left(- \frac{3 \sqrt{3}}{2 \sqrt[3]{3 \sqrt{438} + 63}} + \frac{\sqrt{3} \sqrt[3]{3 \sqrt{438} + 63}}{2}\right)\right) \left(- \frac{\sqrt[3]{3 \sqrt{438} + 63}}{2} - \frac{3}{2 \sqrt[3]{3 \sqrt{438} + 63}} + 7 + i \left(- \frac{\sqrt{3} \sqrt[3]{3 \sqrt{438} + 63}}{2} + \frac{3 \sqrt{3}}{2 \sqrt[3]{3 \sqrt{438} + 63}}\right)\right) \left(\frac{3}{\sqrt[3]{3 \sqrt{438} + 63}} + \sqrt[3]{3 \sqrt{438} + 63} + 7\right)$$
=
406
$$406$$
406
Numerical answer [src]
x1 = 4.19540092945257 + 3.82064495073103*i
x2 = 12.6091981410949
x3 = 4.19540092945257 - 3.82064495073103*i
x3 = 4.19540092945257 - 3.82064495073103*i