5a2=5a+280

Solution for 5a2=5a+280 equation:

5a^2=5a+280

We move all terms to the left:

5a^2-(5a+280)=0

We get rid of parentheses

5a^2-5a-280=0

a = 5; b = -5; c = -280;
Δ = b2-4ac
Δ = -52-4·5·(-280)
Δ = 5625
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5625}=75$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-5)-75}{2*5}=\frac{-70}{10}
=-7
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+75}{2*5}=\frac{80}{10}
=8
$