1/4x-7/8x=20-40

Solution for 1/4x-7/8x=20-40 equation:

1/4x-7/8x=20-40

We move all terms to the left:

1/4x-7/8x-(20-40)=0


Domain of the equation: 4x!=0

x!=0/4

x!=0

x∈R



Domain of the equation: 8x!=0

x!=0/8

x!=0

x∈R


We add all the numbers together, and all the variables

1/4x-7/8x-(-20)=0

We add all the numbers together, and all the variables

1/4x-7/8x+20=0

We calculate fractions


8x/32x^2+(-28x)/32x^2+20=0

We multiply all the terms by the denominator


8x+(-28x)+20*32x^2=0

Wy multiply elements

640x^2+8x+(-28x)=0

We get rid of parentheses

640x^2+8x-28x=0

We add all the numbers together, and all the variables

640x^2-20x=0

a = 640; b = -20; c = 0;
Δ = b2-4ac
Δ = -202-4·640·0
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-20}{2*640}=\frac{0}{1280}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+20}{2*640}=\frac{40}{1280}
=1/32
$