28x2-x-15=0

Solution for 28x2-x-15=0 equation:

28x^2-x-15=0

We add all the numbers together, and all the variables

28x^2-1x-15=0

a = 28; b = -1; c = -15;
Δ = b2-4ac
Δ = -12-4·28·(-15)
Δ = 1681
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1681}=41$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-41}{2*28}=\frac{-40}{56}
=-5/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+41}{2*28}=\frac{42}{56}
=3/4
$