Question

Ten minutes until assignment is due...can anyone help me with this question?

Answer 1

Ok using our basic techniques, do you understand how to find f'(x)?

Answer 2

It is given isnt it?

Answer 3

\(\large\rm f(x)=-3g(x)+5x+5\)
\(\large\rm f'(x)=?\)

Answer 4

-3g(x)+5

Answer 5

Hmm you didn't differentiate your g(x)? :O

Answer 6

that is some weird formatting :/ find the derivative of f
where is the g(x) anyway?

Answer 7

Why did g(x) stay the same when you took derivative of f(x)?

Answer 8

:P nevermind. through the weird formatting, I found it

Answer 9

according to the info g'(x) @ 5 is 2x-2

Answer 10

whoa whoa whoa
y = g(x)
y = 2x-2
so 2x-2=g(x)?

Answer 11

zepdrix is right, you need the derivative of g(x) as well because there's product rule going on for f(x) = -3g(x) term

Answer 12

No product rule.
You just simply didn't take a derivative of the entire first term.

Answer 13

-3g(x)
leave -3 alone deal with g(x) which is g'(x) + leave g(x) deal with -3 which is 0 due to -3 being a constant. unless you're treating g(x) as a constant too.

Answer 14

Im a little lost

Answer 15

Where you at banana man?
You simply forgot to take the derivative of the first term.
\(\large\rm f(x)=-3g(x)+5x+5\)
\(\large\rm f'(x)=-3g'(x)+5\)
understand?

Answer 16

yea definitely. back on track.

Answer 17

So now we evaluate this derivative at x=-5,
\(\large\rm f'(-5)=-3g'(-5)+5\)

Answer 18

you need g(x) to grab the derivative of g(x)
because finding f'(-5)
ahahahhahah ... stuckage

Answer 19

If y=2x-2 is the equation of the line tangent to g(x) at x=-5,
then g'(-5) gives us THE SLOPE of that equation, ya?

Answer 20

Yup

Answer 21

-12

Answer 22

So which value is the slope in the equation? y=2x-2
m=2, yes?
Therefore g'(-5)=2.

Answer 23

-12?? Hmm...

Answer 24

y=g(x)
y=2x-2
g(x) = 2x-2
g'(x) = 2

Answer 25

I put 41 but got it wrong

Answer 26

g'(-5) = 2
so now
f'(-5) = -3g'(-5)+5
we know that g'(-5) = 2 so plug that in
f(-5) = -3(2)+5
now solve that

Answer 27

shoots forgot the ' for f'(-5)

Answer 28

f'(-5) = -3g'(-5)+5
we know that g'(-5) = 2 so plug that into the equation
f'(-5) = -3(2)+5
now solve

Answer 29

got it, thanks