Question

For f(x)=-2x-13, find f(x) when x=5
Can someone please help me?

Answer 1

What helps with a problem like this is replacing f(x) with y. The equation becomes y=-2x-13. Now you just need to plug on for x. y=-2 (5)-13. that becomes y = -10 - 13. y= -23. you have to change y back to f(x) so, f(x) = - 23.

Answer 2

f(x) = -38

Explanation:

well f(x) is the same thing as y so just write it as y so its easier to understand.

y = -2x -13

take the x value they give you which in this case is 5 and plug it in to the x in your equation.

y = -2(5) -13

now just use a calculator or something and find that

y = -25 - 13

and finally

y = -38

now just change y back to f(x) if needed

hope this helps :)