For the equation x^2 - 2x - 8 = y find: (a) The roots. (b) The y-intercept. (c) The coordinate of the turning point

(a) Several methods to do this, simplest would be to factorise the quadratic into (x - 4)(x + 2) = 0 and from here see that root occur at x = 4 and x = -2.(b) Substitute x = 0 into the equation 0^2 - 20 - 8 = - 8 = y, so y-intercept at y = -8.(c) Quadratic equations are symmetrical so the x coordinate of the tuning point occurs midway between the 2 roots so x = 1, substitute this into the equation to get out y = 1^2 - 12 - 8 = -9, so the coordinate of the tuning point is (1,-9).

BC
Answered by Benjamin C. Maths tutor

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