(a) Find the equation of the normal to the curve y = (x - x + 1)(x - 2) at the point where the curve cuts the X - axis. (b) The coordinates of the pints P, Q and R are (-1, 2), (5, 1) and (3, -4) respectively. Find the equation of the line joining Q and the midpoint of .
Explanation
(a) From y = (x - x + 1)(x - 2) - x + 1)(x - 2) = x- 3x + 3x - 2 dy/dx = 3x - 6x + 3 =x - 2x + 1 (x - 1) = 0 twice ; x = 1 y = (1 - 1 + 1) (1-2) ; y = -1 Gradient m of tangent = y/x = -1/1 = -1 Using mm = -1 Gradient, m of normal =1 Using y-y = m(x - x) y + 1 = x - 1; x - y - 2 = 0
x,y = ( -1, 2), , x,y, =(3, -4) Mid point of PR = = (1-1) Using = = ; = 2(y-1) = x - 5; 2y - 2 = x - 5 2y - x = -3 x - 2y -3 =0