Let F=f+g and G=3f-g
find F'(1)

Question

Let F=f+g  and G=3f-g
find F'(1)

akshay_budhkar · Answer

Do u have f and g given?

precal · Answer

I have a graph, would you like me to upload it?

akshay_budhkar · Answer

yea sure i will have a look at it

precal · Answer

Ok, give me a minute I have to scan it.

anonymous · Answer

Akshay had a good eyes :P

precal · Answer

attachment

precal · Answer

Thanks for waiting.
I think
F ' = f ' + g '
G ' = 3f ' - g'    not sure about G '

precal · Answer

I am not sure what to do with F=f+g

anonymous · Answer

This is the hard way: Use interpolation to find the value of f(x) and g(x) in polynomial form and then use the derivatives.

precal · Answer

sorry not sure how to do that.  Interpolation?

akshay_budhkar · Answer

@Fool o_O??? What is the easy way?

I would go for finding f and g as a general function ( it is a line) and add the general equations then differentiate and the substitute 1

precal · Answer

ok let me write the equations

precal · Answer

so, I only need the equation where x=1
so f(x)=-3x+10
now let me do g(x)

precal · Answer

g(x) is x+1
F=f+g
F=-3x+10+x+1
F=-2x+11
F'=-2
F'(1) = -2
correct?

precal · Answer

yes, I am right.  Lookedin the back of my book.
Thanks for your help

akshay_budhkar · Answer

hehe when u wrote ur function f i got it u will get your answer!! i was sure of it =D