Question

Solve x2 - 3x = 28 by factoring.

Answer 1

x = -4 or x = 7

Answer 2

x = -4 or x = 7

Explanation:

`x^2-3x=28\qquad\text{subtract 28 from both sides}\\\\x^2-3x-28=0\\\\x^2+4x-7x-28=0\qquad\text{distribute}\\\\x(x+4)-7(x+4)=0\\\\(x+4)(x-7)=0\iff x+4=0\ \vee\ x-7=0\\\\x+4=0\qquad\text{subtract 4 from both sides}\\\boxed{x=-4}\\\\x-7=0\qquad\text{add 7 to both sides}\\\boxed{x=7}`