Finding Inputs of Functions (Junior Cert Mathematics): Quizzes

Solving for $x$ when we know $f(x)$

$f(x) = 5x - 3$

$12$

Look at the function and given output

Set the function equal to the output

$5x - 3 = 12$

Add $3$ to both sides

$5x = 15$

$x = 3$

Substitute $x$ back into the function