Factor completely.
-$$x ^ { 2 } - x - 42$$
A) $( x + 7 ) ( x - 6 )$
B) $( x - 7 ) ( x + 7 )$
C) $( x + 6 ) ( x - 7 )$
D) $( x + 1 ) ( x - 13 )$

Question

Quizplus · Accepted Answer

We need to find two numbers whose product is negative 42 and whose sum is negative 1. The only such numbers are -7 and 6. Therefore, we can write the expression as:
$$x ^ { 2 } - x - 42 = (x - 7)(x + 6)$$
So the correct answer is choice C.

Factor Completely x2−x−42x ^ { 2 } - x - 42x2−x−42

Factor Completely $x ^ { 2 } - x - 42$