Find the derivative of f(x) = 4x + 7 at x = 5

Question

agent0smith · Answer

Can you find the derivative of f(x) first?

agent0smith · Answer

This is from a precalc class right?

anonymous · Answer

@agent0smith yes c:

anonymous · Answer

im confused

agent0smith · Answer

Use 

f'(x) = (f(x+h) - f(x))/h familiar with this...? Equation editor is not working btw

anonymous · Answer

sorta

agent0smith · Answer

first, f(x+h) = 4(x+h) +7

then use the above formula

f'(x) = ( 4(x+h) + 7 - (4x+7) )/h

anonymous · Answer

do i start solving?

agent0smith · Answer

Yep, simplify

anonymous · Answer

so 4?

agent0smith · Answer

Yep!

e.mccormick · Answer

Just as a thing to remember, the derivative is the slope of the tangent line.  Well, if something is a straight line, it is its own tangent line.  If it is curved there is more to it, but for simple equations with no powers or rational equations involved, you are looking for the slope.

agent0smith · Answer

^yeah, but with the wording of the question, i think they're looking for use of that method.

e.mccormick · Answer

You know better than me, seeing as it is what you do!  I'm just adding in some food for thought.

agent0smith · Answer

Yeah, and you know you've done the work right if you get the slope of the line.