7/9y+3/7y=4/5

Solution for 7/9y+3/7y=4/5 equation:

7/9y+3/7y=4/5

We move all terms to the left:

7/9y+3/7y-(4/5)=0


Domain of the equation: 9y!=0

y!=0/9

y!=0

y∈R



Domain of the equation: 7y!=0

y!=0/7

y!=0

y∈R


We add all the numbers together, and all the variables

7/9y+3/7y-(+4/5)=0

We get rid of parentheses

7/9y+3/7y-4/5=0

We calculate fractions


(-1764y^2)/1575y^2+1225y/1575y^2+675y/1575y^2=0

We multiply all the terms by the denominator


(-1764y^2)+1225y+675y=0

We add all the numbers together, and all the variables

(-1764y^2)+1900y=0

We get rid of parentheses

-1764y^2+1900y=0

a = -1764; b = 1900; c = 0;
Δ = b2-4ac
Δ = 19002-4·(-1764)·0
Δ = 3610000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3610000}=1900$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1900)-1900}{2*-1764}=\frac{-3800}{-3528}
=1+34/441
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1900)+1900}{2*-1764}=\frac{0}{-3528}
=0
$