If f(x)=3x²−x³, find f′(1) and use it to find an equation of the tangent line to the curve y=3x²−x³ at the point (1,2) without using power rule.
A) f′(1)=3 and the tangent line equation is y=3x−1
B) f′(1)=3 and the tangent line equation is y=3x+2
C) f′(1)=2 and the tangent line equation is y=2x−1
D) f′(1)=2 and the tangent line equation is y=2x+1