Solve 4x+16+x^4-2x^3-10x^2

$$4 x + 16 + x ^ { 4 } - 2 x ^ { 3 } - 10 x ^ { 2 }$$

Factor

$$\left(x-4\right)\left(x+2\right)\left(x^{2}-2\right)$$

Solution Steps

To factor the expression, solve the equation where it equals to 0.

$$x^{4}-2x^{3}-10x^{2}+4x+16=0$$

By Rational Root Theorem, all rational roots of a polynomial are in the form \frac{p}{q}, where p divides the constant term 16 and q divides the leading coefficient 1. List all candidates \frac{p}{q}.

$$±16,±8,±4,±2,±1$$

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^{4}-2x^{3}-10x^{2}+4x+16 by x+2 to get x^{3}-4x^{2}-2x+8. To factor the result, solve the equation where it equals to 0.

$$x^{3}-4x^{2}-2x+8=0$$

By Rational Root Theorem, all rational roots of a polynomial are in the form \frac{p}{q}, where p divides the constant term 8 and q divides the leading coefficient 1. List all candidates \frac{p}{q}.

$$±8,±4,±2,±1$$

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.

$$x=4$$

By Factor theorem, x-k is a factor of the polynomial for each root k. Divide x^{3}-4x^{2}-2x+8 by x-4 to get x^{2}-2. To factor the result, solve the equation where it equals to 0.

$$x^{2}-2=0$$

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, 0 for b, and -2 for c in the quadratic formula.

$$x=\frac{0±\sqrt{0^{2}-4\times 1\left(-2\right)}}{2}$$

Do the calculations.

$$x=\frac{0±2\sqrt{2}}{2}$$

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

$$x=-\sqrt{2} x=\sqrt{2}$$

Rewrite the factored expression using the obtained roots. Polynomial x^{2}-2 is not factored since it does not have any rational roots.

$$\left(x-4\right)\left(x+2\right)\left(x^{2}-2\right)$$

Evaluate

$$\left(x-4\right)\left(x+2\right)\left(x^{2}-2\right)$$