1/5x+2x=-4

Solution for 1/5x+2x=-4 equation:

1/5x+2x=-4

We move all terms to the left:

1/5x+2x-(-4)=0


Domain of the equation: 5x!=0

x!=0/5

x!=0

x∈R


We add all the numbers together, and all the variables

2x+1/5x+4=0

We multiply all the terms by the denominator


2x*5x+4*5x+1=0

Wy multiply elements

10x^2+20x+1=0

a = 10; b = 20; c = +1;
Δ = b2-4ac
Δ = 202-4·10·1
Δ = 360
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{360}=\sqrt{36*10}=\sqrt{36}*\sqrt{10}=6\sqrt{10}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-6\sqrt{10}}{2*10}=\frac{-20-6\sqrt{10}}{20}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+6\sqrt{10}}{2*10}=\frac{-20+6\sqrt{10}}{20}
$