Derrivative rules

Question

find an equation for the line tangent to the graph of f(x)= 8x/x+8

at the point (1,0.888888888888889)

y=

im stuck please help

Answer 1

indeed (1, 8/9) is on the graph of the function

y = f(x) = (8x)/(x+8)

notice the parenthesis... please use them!

quotient rule..

y' = f'(x) = [(x+8)(8) - (8x) ] / (x+8)^2

M = f'(1) = [ 9*8 - 8*1]/(1+8)^2

= [ 72-8]/9^2

= 64/81

B = y - mx = 8/9 - (64/81)*1

= 8/9 - 64/81

= 8/9*9/9 - 64/81

= 72/81 - 64/81

= 8/81

y = 64/81 x + 8/81

Answer 2

Hi Derick, take a look! –Joel