7a^2-a-8=0

Solution for 7a^2-a-8=0 equation:

7a^2-a-8=0

We add all the numbers together, and all the variables

7a^2-1a-8=0

a = 7; b = -1; c = -8;
Δ = b2-4ac
Δ = -12-4·7·(-8)
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-15}{2*7}=\frac{-14}{14}
=-1
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+15}{2*7}=\frac{16}{14}
=1+1/7
$