-2/5y-1/7y=665

Solution for -2/5y-1/7y=665 equation:

-2/5y-1/7y=665

We move all terms to the left:

-2/5y-1/7y-(665)=0


Domain of the equation: 5y!=0

y!=0/5

y!=0

y∈R



Domain of the equation: 7y!=0

y!=0/7

y!=0

y∈R


We calculate fractions


(-14y)/35y^2+(-5y)/35y^2-665=0

We multiply all the terms by the denominator


(-14y)+(-5y)-665*35y^2=0

Wy multiply elements

-23275y^2+(-14y)+(-5y)=0

We get rid of parentheses

-23275y^2-14y-5y=0

We add all the numbers together, and all the variables

-23275y^2-19y=0

a = -23275; b = -19; c = 0;
Δ = b2-4ac
Δ = -192-4·(-23275)·0
Δ = 361
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{361}=19$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-19)-19}{2*-23275}=\frac{0}{-46550}
=0
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-19)+19}{2*-23275}=\frac{38}{-46550}
=-1/1225
$