Question

find the equation of the line tangent to the graph of y=3x-cosx at x=0.

Answer 1

Take the derivative, evaluate at zero. Use that value as the slope that goes through the point of the function at zero.

Answer 2

ooh thanks

Answer 3

well what i got is derivative is 3+sinx?

Answer 4

yeah, evaluate at x=0.

Answer 5

hmm i got derivative = 3+sinx

Answer 6

What is sin(0)?

Answer 7

why dont u evalute 0 at cosx? isnt that the original equation

Answer 8

I made a mistake above. The derivative evaluates to three at x=0, and the function evaluates to -1 at x=0. So, the tangent line is y=3x -1

Answer 9

oh that is one of my answer choices

Answer 10

still slightly confused so u plugged in zero to the derivative and the original function?

Answer 11

OK, summary: The derivative at the value of x finds the slope of the tangent line. The function at the value of x gives the point the tangent line goes through. Combine these two facts to get the equation of the tangent line.

Answer 12

ook thanks so much

Answer 13

No sweat.