Question

F(x) = -2x + 10, If f(x)= 40, what is the value of x? (find the input)

Answer 1

f(x) = -2x + 10

If f(x)= 40

By using equation,

or, 40=-2x+10

or, 40-10=-2x

or, 30=-2x

or, 30/-2=x

Therefore x=-15

Answer 2

-15

Explanation:

set it up

f(40)=-2x+10

40=-2x+10

subtract ten

30=-2x

divide by -2 to isolate the x

-15=x