Find the real roots of {eq}x^4 = 16 {/eq}.

## Question:

Find the real roots of {eq}x^4 = 16 {/eq}.

## Roots of polynomials:

The roots of a polynomial {eq}P(x) {/eq} are the solutions to the equation

$$P(x)=0 $$

Techniques for solving this equation include factoring, using the quadratic equation, and the rational roots theorem.

## Answer and Explanation: 1

Here, we have to find the real roots of {eq}x^{4}-16. {/eq} That is, we have to solve the equation

$$x^4-16=0. $$

Factoring, the polynomial, we get:

$$\begin{align} x^4-16&=0 \\ (x^2-4)(x^2+4)&=0 \\ (x-2)(x+2)(x^2+4)&=0 \end{align} $$

Therefore, the equation is true if {eq}x-2=0 {/eq} (that is, if {eq}x=2) {/eq} or if {eq}x+2=0 {/eq} (that is, if {eq}x=-2) {/eq} or if {eq}x^2+4=0 {/eq} (that is, if {eq}x^2=-4). {/eq} This last equation has no real roots, so the only real roots of {eq}x^{4}=16 \text{ are }\boxed{+2, -2}. {/eq}

#### Learn more about this topic:

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Chapter 20 / Lesson 3Learn about polynomial equations and polynomial formulas. Understand how to find the roots of a polynomial and how to generate polynomials from roots.