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Solve for x.x³ + x² = 4x + 4x = [?], [ ], [ ]Order your answers from smallest tolargest. Enter the number that belongs inthe green box.Note: Enter any fractional answers in decimal form.Enter

Solve for x.x³ + x² = 4x + 4x = [?], [ ], [ ]Order your answers from smallest tolargest-example-1
User Austine
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1 Answer

5 votes

To solve this problem we will factor the given polynomial.

First, we rewrite the given equation as follows:


x^3+x^2-4x-4=0.

Now, notice that:


x^3+x^2-4x-4=(x+1)(x+2)(x-2).

Therefore:


\begin{gathered} x^3+x^2-4x-4=0\text{ if and only if} \\ \left(x+1\right)\left(x+2\right)\left(x-2\right)=0. \end{gathered}

Recall that:


ab=0,\text{ if and only if a=0 or b=0.}

Therefore:


\left(x+1\right)\left(x+2\right)\left(x-2\right)=0\text{ if \lparen x+1\rparen=0 or \lparen x+2\rparen=0 or \lparen x-2\rparen=0.}

Solving each equation for x, we get:


x=-1,\text{ x=-2, x=2.}

Answer:


?=-2.