Solve x^3+x=10

$${ x }^{ 3 } +x=10$$

Solve for x (complex solution)

$$x=-1-2i$$

$$x=2$$

$$x=-1+2i$$

Solution Steps

Subtract 10 from both sides.

$$x^{3}+x-10=0$$

By Rational Root Theorem, all rational roots of a polynomial are in the form \frac{p}{q}, where p divides the constant term -10 and q divides the leading coefficient 1. List all candidates \frac{p}{q}.

$$±10,±5,±2,±1$$

Find one such root by trying out all the integer values, starting from the smallest by absolute value. If no integer roots are found, try out fractions.

$$x=2$$

By Factor theorem, x-k is a factor of the polynomial for each root k. Divide x^{3}+x-10 by x-2 to get x^{2}+2x+5. Solve the equation where the result equals to 0.

$$x^{2}+2x+5=0$$

All equations of the form ax^{2}+bx+c=0 can be solved using the quadratic formula: \frac{-b±\sqrt{b^{2}-4ac}}{2a}. Substitute 1 for a, 2 for b, and 5 for c in the quadratic formula.

$$x=\frac{-2±\sqrt{2^{2}-4\times 1\times 5}}{2}$$

Do the calculations.

$$x=\frac{-2±\sqrt{-16}}{2}$$

Solve the equation x^{2}+2x+5=0 when ± is plus and when ± is minus.

$$x=-1-2i x=-1+2i$$

List all found solutions.

$$x=2 x=-1-2i x=-1+2i$$

Solve for x

$$x=2$$

Solution Steps

Subtract 10 from both sides.

$$x^{3}+x-10=0$$

By Rational Root Theorem, all rational roots of a polynomial are in the form \frac{p}{q}, where p divides the constant term -10 and q divides the leading coefficient 1. List all candidates \frac{p}{q}.

$$±10,±5,±2,±1$$

Find one such root by trying out all the integer values, starting from the smallest by absolute value. If no integer roots are found, try out fractions.

$$x=2$$

By Factor theorem, x-k is a factor of the polynomial for each root k. Divide x^{3}+x-10 by x-2 to get x^{2}+2x+5. Solve the equation where the result equals to 0.

$$x^{2}+2x+5=0$$

All equations of the form ax^{2}+bx+c=0 can be solved using the quadratic formula: \frac{-b±\sqrt{b^{2}-4ac}}{2a}. Substitute 1 for a, 2 for b, and 5 for c in the quadratic formula.

$$x=\frac{-2±\sqrt{2^{2}-4\times 1\times 5}}{2}$$

Do the calculations.

$$x=\frac{-2±\sqrt{-16}}{2}$$

Since the square root of a negative number is not defined in the real field, there are no solutions.

$$x\in \emptyset$$

List all found solutions.

$$x=2$$