(7-2y)y+7-2y=4

Solution for (7-2y)y+7-2y=4 equation:

(7-2y)y+7-2y=4

We move all terms to the left:

(7-2y)y+7-2y-(4)=0

We add all the numbers together, and all the variables

(-2y+7)y-2y+7-4=0

We add all the numbers together, and all the variables

-2y+(-2y+7)y+3=0

We multiply parentheses

-2y^2-2y+7y+3=0

We add all the numbers together, and all the variables

-2y^2+5y+3=0

a = -2; b = 5; c = +3;
Δ = b2-4ac
Δ = 52-4·(-2)·3
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-7}{2*-2}=\frac{-12}{-4}
=+3
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+7}{2*-2}=\frac{2}{-4}
=-1/2
$