Question

solve y=f(x) for x then find the input when the output is 6

f(x)=x+9

Answer 1

x = -3

So to figure this out we can readjust the equation to make it easier to solve

$f(x) = x + 9$ is equal to $x+9 = 6$

From here we can just subtract 9 from both sides and we get our answer!

$x+(9-9) = (6-9)\\x = -3$