Q.) Find k, in the function f(x) = x(power 3) + 2(x(power 2)) + x + k, if the equation of the tangent line to f(x) is y= 3x -1. Solution slope of tangent : 3 3x2 + 4x + 1 = 3 3x2 + 4x - 2 = 0 x = -4 ± sqrt [ 16 + 24 ]/6 x = [-4 ± 210]/6 x = [-2 ± 10]/3 y = -2 ± 10 - 1 y = -3 ± 10 ther are two points so substitute them in the main f(x) and get value of K answer !!!1.