n+(2/7)n=81

Solution for n+(2/7)n=81 equation:

n+(2/7)n=81

We move all terms to the left:

n+(2/7)n-(81)=0


Domain of the equation: 7)n!=0

n!=0/1

n!=0

n∈R


We add all the numbers together, and all the variables

n+(+2/7)n-81=0

We multiply parentheses

2n^2+n-81=0

a = 2; b = 1; c = -81;
Δ = b2-4ac
Δ = 12-4·2·(-81)
Δ = 649
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-\sqrt{649}}{2*2}=\frac{-1-\sqrt{649}}{4}
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{649}}{2*2}=\frac{-1+\sqrt{649}}{4}
$