00:01
For this question, we're asked to solve this initial value problem by using the laplace transform, and eventually i'm going to use this shifting property.
00:08
But first, let me rewrite this differential equation using unit step functions.
00:13
So i still have y ' plus 5y, but now this is equal to 11 times u of t minus 3, and then minus u of t minus 6.
00:28
So this function right here, it's only equal to 11 when t is between 3 and 6.
00:35
Now i'll take the laplace transform of this differential equation.
00:39
So i'll get s times y of s minus y of 0, and then plus 5 times y of s.
00:51
This is equal to 11 e to the negative 3s over s, and then minus 11 e to the negative 6s over s.
01:05
And we know that this is true from the shifting property, or you could always just look this up on a laplace transform table.
01:13
Right, so let me group my y of s terms.
01:16
I'll have s plus 5, and then we're told that y of 0, this is equal to 5.
01:23
So i have minus 5, and then on the right -hand side of the equation, i still have this, so that doesn't change.
01:32
Then i can solve for y of s by moving the 5 over, and then dividing through by s plus 5...