Hello!
You have to put the numbers in for the variables in the equation
[tex] \frac{7b - 12}{2ac} [/tex]
Put the numbers in
[tex] \frac{7(4) - 12}{4(-2)(7)} [/tex]
Combine like terms
[tex] \frac{28 - 12}{-56} [/tex]
[tex] \frac{16}{-56} [/tex]
The is is [tex] \frac{16}{-56}[/tex] or about -0.29
Hope this help!
