SAT Math Multiple Choice Practice Question 186: Answer and Explanation
10. If x2 + 2ax + a2 = 16, which of the following could be the value of x + a?
Correct Answer: B
B. The trick to this problem is to see that x2 + 2ax + a2 can be factored into (x + a)2. Now you can rewrite the equation as (x + a)2 = 16, so you know that x + a has to equal 4 or -4. Choice (B) is the right answer.