Author Topic: hellpppp!!! (Read 868 times) Tweet Share

lacoste · « **on:** June 11, 2009, 07:04:08 pm »

If f(x)= ax^2 + bx, solve for a and b given that the gradient at (3,5) = 1

thanks!!

dcc · « **Reply #1 on:** June 11, 2009, 08:18:52 pm »

So we have the information given to us that $f(3) = 5$ and $f'(3) = 1$

Therefore:

$f(3) = 5 \implies 5 = 9a + 3b$

$f'(x) = 2ax + b$

$f'(3) = 1 \implies 1 = 6a + b$

Solving these simultaneously, we find that:

$f(x) = \frac{7}{3}x - \frac{2}{9} x^2$

Search the forums now!

We have moved!

Author Topic: hellpppp!!! (Read 868 times) Tweet Share

lacoste

hellpppp!!!

dcc

Re: hellpppp!!!

Recent Posts

User:
Password: