Practice GMAT Data Sufficiency Question

What is the value of (n + 1)²?

A)	Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B)	Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C)	BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D)	EACH statement ALONE is sufficient.
E)	Statement (1) and (2) TOGETHER are NOT sufficient to answer the question asked, and additional data are needed.

Correct Answer: D

Evaluate Statement (1) alone.
1. Try to solve for n:
  n² - 6n = -9
  n² - 6n + 9 = 0
  (n - 3)² = 0
  n - 3 = 0
  n = 3
  With one value for n, we can find a single value for (n + 1)²
2. Statement (1) alone is SUFFICIENT.
Evaluate Statement (2) alone.
1. Expand the terms and simplify them:
  n² - 2n + 1 = n² – 5
  -2n + 1 = -5
  -2n + 6 = 0
  6 = 2n
  n = 3
  With one value for n, we can find a single value for (n + 1)²
2. Statement (2) alone is SUFFICIENT.
Since Statement (1) alone is SUFFICIENT and Statement (2) alone is SUFFICIENT, answer D is correct.