-3/8x-1/5x=7

Solution for -3/8x-1/5x=7 equation:

-3/8x-1/5x=7

We move all terms to the left:

-3/8x-1/5x-(7)=0


Domain of the equation: 8x!=0

x!=0/8

x!=0

x∈R



Domain of the equation: 5x!=0

x!=0/5

x!=0

x∈R


We calculate fractions


(-15x)/40x^2+(-8x)/40x^2-7=0

We multiply all the terms by the denominator


(-15x)+(-8x)-7*40x^2=0

Wy multiply elements

-280x^2+(-15x)+(-8x)=0

We get rid of parentheses

-280x^2-15x-8x=0

We add all the numbers together, and all the variables

-280x^2-23x=0

a = -280; b = -23; c = 0;
Δ = b2-4ac
Δ = -232-4·(-280)·0
Δ = 529
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{529}=23$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-23)-23}{2*-280}=\frac{0}{-560}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-23)+23}{2*-280}=\frac{46}{-560}
=-23/280
$