Kirill Z. answered • 04/04/14
Tutor
4.8
(230)
Physics, math tutor with great knowledge and teaching skills
For parabola y=ax2+bx+c vertex x-coordinate is given by:
xv=-b/(2a);
In your case, xv=-9/((-5)*2)=0.9
FYI: y-coordinate of a vertex is given by:
yv=c-b2/(4a)
Philip P.
That should be - 5*(9/10)2 = -4.05 so
f(x) = 5(x-(0.9))2 + 4.95
Report
04/04/14
Philip P.
f(x) = a(x-h)2 + k
In this form, the x coordinate of the vertex = h. To put the equation in this form, factor out the coefficient of x then complete the square:
f(x) = 5x2 + 9x + 9
f(x) = 5(x2 + 9x/5 + (9/10)2) + 9 - (9/10)2
f(x) = 5(x - (-0.9))2 + 8.19
xv = h = -0.9
04/04/14