Question

Select the correct answer.

Find the solution(s) for x in the equation below.
x(x - 1) = 42
А. x = -7; x = -6
B. x = 7; x = 6
C. x = 7; x = -6
D. x = 6

Answer 1

7 and -6 (corresponding to Answer C)

Explanation:

Solve x(x - 1) = 42 for x.

To do this, first perform the indicated multiplication and then rearrange the terms in standard quadratic function order:

x^2 - x - 42 = 0

Factoring yields (x - 7)(x + 6) = 0,

leadng to roots 7 and -6 (corresponding to Answer C)