How do you find the vertex and intercepts for f(x)=5x2+3x+8?

1 Answer
Nov 17, 2015

Find vertex and intercepts of f(x)=5x2+3x+8

Explanation:

x-coordinate of vertex:
x=b2a=310=310.
y-coordinate of vertex:
f(310)=5(9100)+3(310)+8==45100+90100+800100=845100=8.45
To find y-intercept, make x = 0 --> y = 8
To find x-intercepts, make y = 0. Solve the quadratic equation:
5x2+3x+8=0.
Since a - b + c = 0, use shortcut: the 2 real roots are:x=1 and
x=ca=85