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

Related Maths GCSE answers

All answers ▸

Multiply out and simplify (x+7)(x-3)


Solve 9x +1> 2x +3


a) Find the equation of the line that passes through (2,10) and (4,16) b) Find the point where the line in (a) intersects the line y=5x-2


Solve the simultaneous equations: 3x + 2y = 4 and 4x + 5y = 17