# GRE® Quant Practice | Algebra Q4

#### Select One or More Answers | Functions

The GRE maths sample question given below is a select one or more answers type question in Algebra. Computing values of Functions is the concept tested in the question. A medium difficulty GRE Quantitative Reasoning practice question.

Question 4 : If f(x) = x2 + 4, which of the following is equal to f(9)?

1. f(13)
2. f(-3)
3. f(-9)
4. f(f(√5))
5. f(f(√13))
6. f(f(-√5))

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### Explanatory Answer | GRE Functions Practice

#### Step 1 of solving this GRE Functions Question: Compute the value of f(9)

f(x) = x2 + 4
f(9) = 92 + 4 = 85

#### Step 2 of solving this GRE Functions Question: Compute values for each answer option

Option A: f(3) = 32 + 4 = 13.
13 is not equal to f(9).
Hence, this option is not an answer.

Option B: f(13) = 132 + 4 = 173
173 is not equal to f(9).
Hence, this option is not an answer.
Option C: f(-9) = (-9)2 + 4 = 85
85 is equal to f(9).
Hence, this option is one of the right answers.
Option D: f(f(√5)) = f((√5)2 + 4) = f(9) = 85
85 is equal to f(9).
Hence, this option is one of the right answers.
Option E: f(f(√13)) = f((√13)2 + 4) = f(17) = 172 + 4 = 293
293 is not equal to f(9).
Hence, this option is not an answer.
Option F: f(f(-√5)) = f((-√5)2 + 4) = f(9) = 85
85 is equal to f(9).
Hence, this option is one of the right answers.

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