Question

How do you find the vertex and intercepts for `f(x)=-5x^2+3x+8`?

Answer 1

Find vertex and intercepts of `f(x) = -5x^2 + 3x + 8`

Explanation:

x-coordinate of vertex:
`x = -b/(2a) = -3/-10 = 3/10.`
y-coordinate of vertex:
#f(3/10) = - 5(9/100) + 3(3/10) + 8 = = -45/100 + 90/100 + 800/100 = 845/100 = 8.45#
To find y-intercept, make x = 0 --> y = 8
To find x-intercepts, make y = 0. Solve the quadratic equation:
`- 5x^2 + 3x + 8 = 0.`
Since a - b + c = 0, use shortcut: the 2 real roots are:`x = -1` and
`x = -c/a = 8/5`