From maths online.
I don't understand how to get to the result desired.
u= 3x
du/dx= 3
v= (x+5)^3
dv/dx= 3(x+5)^2 { i multiplied by the derivative of the inside, which is one}
NOW INSIDE TERMS ( multiplied) + OUTSIDE TERMS ( multiplied)
dy/dx= 3(x+5)^3 + 9x (x+5)^2 { take out 3 (x+5)^2 as a common factor}
= 3 ( x+5 )^2 [ (x+5) +3x]
= 3 ( x+5)^2 ( 4x+5)
im a little worried why you were up at 4 am in the morning doing maths, you dont need to study 24/7