Find the derivative:- y' = 8x - 6x^2 This is the slope in terms of x. When x = a , the slope is 8a - 6a^2
(b) equation of tangent line at x1,y1 is y- y1 = (8x - 6x^2)( x - x1) , so at (1,11) it is y - 11 = (8(1) - 6((1)^2) ) (x - 1) y = 2(x - 1) + 11 y = 2x + 9 (answer)
At (2,9) y - 9 = (16-24)(x - 2) y - 9 = -8x + 16 y = -8x + 25 answer
