Scott Woodbury-Stewart

GMAT OFFICIAL GUIDE PS – If a(a + 2) = 24 and…

If a(a + 2) = 24 and…

Solution:

To solve, we must determine the values of a and b.
We are given a(a+2) = 24 So:

a^2 + 2a – 24 = 0

(a + 6)(a – 4) = 0

a = -6 or a = 4

The second equation containing variable b is algebraically identical to the first one, so b = -6 or b = 4.

Since a cannot equal b, the sum a + b = -6 + 4, or the sum is 4 + (-6), which, in both cases, equals -2.

Answer: B 

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