-7x^2+27x+4=0

Solution for -7x^2+27x+4=0 equation:

-7x^2+27x+4=0

a = -7; b = 27; c = +4;
Δ = b2-4ac
Δ = 272-4·(-7)·4
Δ = 841
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{841}=29$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(27)-29}{2*-7}=\frac{-56}{-14}
=+4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(27)+29}{2*-7}=\frac{2}{-14}
=-1/7
$