The maximum value of the quadratic equation $2x-7-5x^2$ is

The maximum value of $f\left(x\right)=2x-7-5x^2$

$a=-5<0$

$b=2$

$c=-7$

Now, $\frac{4ac-b^2}{4a}=\frac{4(-5)(-7)-2^2}{4(-5)}$

$=\frac{140-4}{-20}=\frac{-136}{20}$

$=-\frac{34}{5}$