Find the slope of the tangent line to the curve defined by x3+2xy2=9x^3 + 2xy^2 = 9x3+2xy2=9 at the point (1,2)(1, 2)(1,2).
−7/8-7/8−7/8
1/81/81/8
−5/8-5/8−5/8
5/85/85/8