Question

double derivative of y = -5cosx be y'' = 5cosx or -cosx? I believe it's + cosx but I wanna make sure.

Answer 1

And what did you get for y'?

Answer 2

y' = 5sinx . I'm assuming the - cancels out since it's already -.

Answer 3

y' is correct
So what is derivative of sin(x)?
And don't forget to bring our constant multiple down.

Answer 4

And yes a negative times a negative is a positive.

Answer 5

cosx

Answer 6

cosx

Answer 7

Right so y''=5cos(x)