math
posted by kwack .
Find the equation of the tangent line to the curve y=5xcosx at the point (pi,–5pi).
The equation of this tangent line can be written in the form y=mx+b where
m=
and b=

y=5x cos x
y'=slope m= 5cosx5xsinx at x=pi
y'=m=5
line equation: y= 5x+b
now to find b, you know the point(PI,5PI) is on it, so
5pi5PI+b so b=0