Solve (x-3)(x+7)=x^2-21

$$( x - 3 ) ( x + 7 ) = x ^ { 2 } - 21$$

Solve for x

$$x=0$$

Steps for Solving Linear Equation

Use the distributive property to multiply x-3 by x+7 and combine like terms.

$$x^{2}+4x-21=x^{2}-21$$

Subtract x^{2} from both sides.

$$x^{2}+4x-21-x^{2}=-21$$

Combine x^{2} and -x^{2} to get 0.

$$4x-21=-21$$

Add 21 to both sides.

$$4x=-21+21$$

Add -21 and 21 to get 0.

$$4x=0$$

Product of two numbers is equal to 0 if at least one of them is 0. Since 4 is not equal to 0, x must be equal to 0.

$$x=0$$