SAT Linear functions Practice Question 5 (Easy)

Math · AlgebraEasy

$x$	$f(x)$
1	5
2	8
3	11

The table shows three values of $x$ and their corresponding values of $f(x)$ for the linear function $f$ . Which equation defines $f$ ?

$f(x) = x + 4$

$f(x) = 5x$

$f(x) = 3x + 2$

$f(x) = 3x + 5$

Show answer and explanation

Answer: C

As $x$ increases by 1, $f(x)$ increases by 3, so the slope is 3. Then $f(1) = 3(1) + b = 5$ gives $b = 2$ . Check: $f(3) = 3(3) + 2 = 11$ .

Choices A and B match the first row only; they fail for $x = 2$ and $x = 3$ .

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