👉 Try now NerdPal! Our new math app on iOS and Android
  1. calculators
  2. Separable Differential Equation

Separable Differential Equation Calculator

Get detailed solutions to your math problems with our Separable Differential Equation step-by-step calculator. Practice your math skills and learn step by step with our math solver. Check out all of our online calculators here.

Go!
Math mode
Text mode
Go!
1
2
3
4
5
6
7
8
9
0
a
b
c
d
f
g
m
n
u
v
w
x
y
z
.
(◻)
+
-
×
◻/◻
/
÷
2

e
π
ln
log
log
lim
d/dx
Dx
|◻|
θ
=
>
<
>=
<=
sin
cos
tan
cot
sec
csc

asin
acos
atan
acot
asec
acsc

sinh
cosh
tanh
coth
sech
csch

asinh
acosh
atanh
acoth
asech
acsch

1

Solved example of separable differential equation

$\frac{dy}{dx}=y^2-4$
2

Group the terms of the differential equation. Move the terms of the $y$ variable to the left side, and the terms of the $x$ variable to the right side of the equality

$\frac{1}{y^2-4}dy=dx$
3

Integrate both sides of the differential equation, the left side with respect to $y$, and the right side with respect to $x$

$\int\frac{1}{y^2-4}dy=\int1dx$

Rewrite the expression $\frac{1}{y^2-4}$ inside the integral in factored form

$\int\frac{1}{\left(y+2\right)\left(y-2\right)}dy$

Rewrite the fraction $\frac{1}{\left(y+2\right)\left(y-2\right)}$ in $2$ simpler fractions using partial fraction decomposition

$\frac{1}{\left(y+2\right)\left(y-2\right)}=\frac{A}{y+2}+\frac{B}{y-2}$

Find the values for the unknown coefficients: $A, B$. The first step is to multiply both sides of the equation from the previous step by $\left(y+2\right)\left(y-2\right)$

$1=\left(y+2\right)\left(y-2\right)\left(\frac{A}{y+2}+\frac{B}{y-2}\right)$

Multiplying polynomials

$1=\frac{\left(y+2\right)\left(y-2\right)A}{y+2}+\frac{\left(y+2\right)\left(y-2\right)B}{y-2}$

Simplifying

$1=\left(y-2\right)A+\left(y+2\right)B$

Assigning values to $y$ we obtain the following system of equations

$\begin{matrix}1=-4A&\:\:\:\:\:\:\:(y=-2) \\ 1=4B&\:\:\:\:\:\:\:(y=2)\end{matrix}$

Proceed to solve the system of linear equations

$\begin{matrix} -4A & + & 0B & =1 \\ 0A & + & 4B & =1\end{matrix}$

Rewrite as a coefficient matrix

$\left(\begin{matrix}-4 & 0 & 1 \\ 0 & 4 & 1\end{matrix}\right)$

Reducing the original matrix to a identity matrix using Gaussian Elimination

$\left(\begin{matrix}1 & 0 & -\frac{1}{4} \\ 0 & 1 & \frac{1}{4}\end{matrix}\right)$

The integral of $\frac{1}{\left(y+2\right)\left(y-2\right)}$ in decomposed fraction equals

$\int\left(\frac{-1}{4\left(y+2\right)}+\frac{1}{4\left(y-2\right)}\right)dy$

Expand the integral $\int\left(\frac{-1}{4\left(y+2\right)}+\frac{1}{4\left(y-2\right)}\right)dy$ into $2$ integrals using the sum rule for integrals, to then solve each integral separately

$\int\frac{-1}{4\left(y+2\right)}dy+\int\frac{1}{4\left(y-2\right)}dy$

Take the constant $\frac{1}{4}$ out of the integral

$\frac{1}{4}\int\frac{-1}{y+2}dy+\int\frac{1}{4\left(y-2\right)}dy$

Take the constant $\frac{1}{4}$ out of the integral

$\frac{1}{4}\int\frac{-1}{y+2}dy+\frac{1}{4}\int\frac{1}{y-2}dy$

Apply the formula: $\int\frac{n}{x+b}dx$$=nsign\left(x\right)\ln\left(x+b\right)+C$, where $b=2$, $x=y$ and $n=-1$

$-\frac{1}{4}\ln\left(y+2\right)+\frac{1}{4}\int\frac{1}{y-2}dy$

Apply the formula: $\int\frac{n}{x+b}dx$$=nsign\left(x\right)\ln\left(x+b\right)+C$, where $b=-2$, $x=y$ and $n=1$

$-\frac{1}{4}\ln\left(y+2\right)+\frac{1}{4}\ln\left(y-2\right)$
4

Solve the integral $\int\frac{1}{y^2-4}dy$ and replace the result in the differential equation

$-\frac{1}{4}\ln\left(y+2\right)+\frac{1}{4}\ln\left(y-2\right)=\int1dx$

The integral of a constant is equal to the constant times the integral's variable

$x$

As the integral that we are solving is an indefinite integral, when we finish integrating we must add the constant of integration $C$

$x+C_0$
5

Solve the integral $\int1dx$ and replace the result in the differential equation

$-\frac{1}{4}\ln\left(y+2\right)+\frac{1}{4}\ln\left(y-2\right)=x+C_0$

Final Answer

$-\frac{1}{4}\ln\left(y+2\right)+\frac{1}{4}\ln\left(y-2\right)=x+C_0$

Struggling with math?

Access detailed step by step solutions to thousands of problems, growing every day!