Which function has the most horizontal tangents?

A.f(x) = 3x^3
B.f(x)=x^4-1
C.f(x)=x^2-2x+1
D.f(x)=x^3+ 3x^2-9x-1

1 answer

D has 2
The others all have 1

Don't forget your Algebra II now that you're taking calculus.