Tuesday, October 25, 2016

`12yy' - 7e^x = 0` Find the general solution of the differential equation

For the given problem: `12yy'-7e^x=0` , we can evaluate this by applying variable separable differential equation in which we express it in a form of `f(y) dy = f(x)dx` .


 Then, `12yy'-7e^x=0` can be rearrange into `12yy'= 7e^x`


Express `y'`  as `(dy)/(dx)` :


`12y(dy)/(dx)= 7e^x`


Apply direct integration in the form of `int f(y) dy = int f(x)dx` :


`12y(dy)/(dx)= 7e^x`


`12ydy= 7e^xdx`


`int12ydy= int 7e^x dx`


For the both side , we apply basic integration property: `int c*f(x)dx= c int f(x) dx`


`12 int ydy= 7int e^x dx`


Applying Power Rule integration: `int u^n du= u^(n+1)/(n+1)` on the left side.


`12int y dy= 12 *y^(1+1)/(1+1)`


               `= (12y^2)/2`


               `=6y^2`


Apply basic integration formula for exponential function: `int e^u du = e^u+C ` on the right side.


`7int e^x dx = 7e^x+C`


Combining the results for the general solution of differential equation:


`6y^2=7e^x+C`


or 


`(6y^2)/6=(7e^x)/6+C`


`y^2 = (7e^x)/6+C`


`y = +-sqrt((7e^x)/6+C)` 

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