A parabola whose equation is y=x2-2x+k has a turning point with coordinates (1,-5). Find the value of K

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- Oct 22nd 2009, 01:22 PMhawk123Question on Quadratic Application
A parabola whose equation is y=x2-2x+k has a turning point with coordinates (1,-5). Find the value of K

- Oct 22nd 2009, 03:08 PMskeeter
- Oct 22nd 2009, 08:13 PMukorov
y

= x^2 - 2x + k

= x^2 - 2x + (-2/2)^2 - (-2/2)^2 + k

= x^2 - 2x + 1 - 1 + k

= (x^2 - 2x + 1) + (k - 1)

= (x - 1)^2 + (k - 1)

= (x - H)^2 + (K)

where (H,K) is the turning point = (1, -5)

hence -5 = k - 1

k = -4