4/y=0.4y=

Solution for 4/y=0.4y= equation:

4/y=0.4y=

We move all terms to the left:

4/y-(0.4y)=0


Domain of the equation: y!=0

y∈R


We add all the numbers together, and all the variables

4/y-(+0.4y)=0

We get rid of parentheses

4/y-0.4y=0

We multiply all the terms by the denominator


-(0.4y)*y+4=0

We add all the numbers together, and all the variables

-(+0.4y)*y+4=0

We multiply parentheses

-0y^2+4=0

We add all the numbers together, and all the variables

-1y^2+4=0

a = -1; b = 0; c = +4;
Δ = b2-4ac
Δ = 02-4·(-1)·4
Δ = 16
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16}=4$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-4}{2*-1}=\frac{-4}{-2}
=+2
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+4}{2*-1}=\frac{4}{-2}
=-2
$