# Find

#### alxn

If F(t) = 4t + 7, find

#### romsek

Math Team
What's the trouble?

Plug t=(3+h) into F(t), and then plug t=3 into it and subtract one from the other, then divide by h.

#### alxn

Do you mean to do like so
(3+h) = 4t + 7
h = 4t + 4

(F(3 + 4t + 4) - F(3))/h

#### mrtwhs

I think what he means is

$F(\mbox{$\,\,\,\,\,\,$})=4(\mbox{$\,\,\,\,\,\,$})+7$

and you fill the parentheses with whatever you want.

#### alxn

(4(3 + h) + 7 - (4(3) + 7)) / h

(12 + 4h + 7 - 12 + 7) / h

4h / h

4

#### topsquark

Math Team
(4(3 + h) + 7 - (4(3) + 7)) / h

(12 + 4h + 7 - 12 $$\displaystyle \color{red} -$$ 7) / h

Your forgot to include the negative on the second 7. As it happens it doesn't change your final answer, which is correct.

-Dan