Evaluating functions Practice Questions (Grade 9)

Evaluating functions. Game on.

Evaluating functions is a grade 9 math skill aligned to Common Core standard HSF.IF.A.2: use function notation, evaluate functions for inputs in their domains, and interpret statements that use function notation in terms of a context. Below are 8 practice questions with answers and step-by-step explanations, drawn from the 10 evaluating functions problems our math games drill.

CCSS HSF.IF.A.210 questions in the bank

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Warm-upeasy

The function $f$ is defined by $f(x) = -3x + 22$ . What is the value of $f(x)$ when $x = 5$ ?

Substitute $x = 5$ : $f(5) = -3(5) + 22 = -15 + 22 = 7$ .

Mid-gameeasy

The function $f$ is defined by $f(x) = 7x - 4$ . What is the value of $f(x)$ when $x = 3$ ?

Substitute $x = 3$ : $f(3) = 7(3) - 4 = 21 - 4 = 17$ .

Mid-gameeasy

The function $f$ is defined by $f(x) = x^{2} - 10$ . What is the value of $f(x)$ when $x = 6$ ?

Substitute $x = 6$ : $f(6) = 6^{2} - 10 = 36 - 10 = 26$ .

Mid-gameeasy

The function $f$ is defined by $f(x) = 3x^{2} + 2$ . What is the value of $f(x)$ when $x = 2$ ?

Substitute $x = 2$ : $f(2) = 3(2)^{2} + 2 = 3(4) + 2 = 12 + 2 = 14$ .

Mid-gameeasy

The function $f$ is defined by $f(x) = x^{2} + 4x$ . What is the value of $f(x)$ when $x = 5$ ?

Substitute $x = 5$ : $f(5) = 5^{2} + 4(5) = 25 + 20 = 45$ .

Mid-gameeasy

The function $f$ is defined by $f(x) = 3 \cdot 2^{x}$ . What is the value of $f(x)$ when $x = 4$ ?

Substitute $x = 4$ : $f(4) = 3 \cdot 2^{4} = 3 \cdot 16 = 48$ .

Mid-gameeasy

The function $f$ is defined by $f(x) = \sqrt{x + 21}$ . What is the value of $f(x)$ when $x = 4$ ?

Substitute $x = 4$ : $f(4) = \sqrt{4 + 21} = \sqrt{25} = 5$ .

Buzzer beatereasy

The function $f$ is defined by $f(x) = \sqrt{2x + 17}$ . What is the value of $f(x)$ when $x = 16$ ?

Substitute $x = 16$ : $f(16) = \sqrt{2(16) + 17} = \sqrt{32 + 17} = \sqrt{49} = 7$ .

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