Find a+b+c if the graph of the equation is a parabola with vertex (5,3) , vertical axis of symmetry, and contains the point (2,0).
\(f(x)=y=ax^2+bx+c\)
\(c=3\)
\(x_1=2\)
\(x_2=8\)
\(a \ is \ negative\)
\(2 = {-b + \sqrt{b^2-12a} \over 2a}\) \(8 = {-b- \sqrt{b^2-12a} \over 2a}\)
\(16a = {-b - \sqrt{b^2-12a} }\)
. plus
\(4a = {-b + \sqrt{b^2-12a} }\)
\(20a=-2b\)
b=-10a
\(4a = {10a - \sqrt{100a^2-12a} }\)
\(-6a= - \sqrt{100a^2-12a}\)
\(36a^2=100a^2-12a\)
\(64a^2=12a\)
\(a=\frac{3}{16}\) Error. CPhill was too fast.