- #1
james_rich
- 23
- 0
okay i need to solve the quadratic y = -x^2 + 5x + 6 and need to find the coordinates of the vertex of the curve
by factorising
y = -(x^2 - 5x - 5)
y = -(x + 1)(x - 6)
so when y = 0, x = -1 and x = 6 (that parts simple)
..............
At the vertex x = (-1 + 6) / 2 = 5/2 (as the curve is symetrical)
so as y = -x^2 + 5x + 6
y = -5/2^2 + 5(-5/2) + 6
y = 25/4 + 50/4 + 24/4
y = 99/4
(this is the answer i got which doesn't look right, and answer book gives a different answer)
can u tell me where i went wrong? thanx
by factorising
y = -(x^2 - 5x - 5)
y = -(x + 1)(x - 6)
so when y = 0, x = -1 and x = 6 (that parts simple)
..............
At the vertex x = (-1 + 6) / 2 = 5/2 (as the curve is symetrical)
so as y = -x^2 + 5x + 6
y = -5/2^2 + 5(-5/2) + 6
y = 25/4 + 50/4 + 24/4
y = 99/4
(this is the answer i got which doesn't look right, and answer book gives a different answer)
can u tell me where i went wrong? thanx