posted by LALA on .
How do i find the derivative of
f(t)= 20- 30/rooot 9 + t^2
heres how i did it
f'(x)= 20' - 30/root(9+t^2) '
= 0 - 30/root(9+t^2) '
f'(x)= 30' (root(9+t^2) - 30(root(9+t^2) '
f'(x)= -30(0.5(9+t^2)^-0.5) (2t)
the answer at the back of the book is 30t/(9+t^2)^1/2.... but i don't knohow to get it.