00:01
The question given wasn't very clear on what the symbols were, so i'm assuming the question marks and the symbols were minus signs since the plus signs printed okay.
00:14
So let's find the inverse laplace of this expression.
00:20
First we'll multiply out the numerator, and i'll color code the coefficients for later use.
00:29
Now we want to use the method of partial fraction, decomposition and that would mean we need to take this and solve for the a, b, and c so that this expression will be equal to the problem that we were given.
00:58
So to begin with, we'll multiply the a by s minus 1, s minus 2, and s plus 1, and we would get this.
01:15
When we multiply the b, minus 2 times s plus 1 we would get this when we multiply the c by s and s minus 1 and s plus 1 we would get this and when we multiplied the d by s and s minus 1 and s minus 2 we'd get this and we're going to collect like terms for example all of the s cubes when written together would be all of the s squared and the s's, and finally the constant.
02:35
Now, in order for our decomposition fractions to be equal to the original single fraction, we would need the coefficient of the s -cubed to be the same as the coefficient of s -cubed in the original.
02:54
So we would have an a plus b plus c plus d, equal to 1.
03:03
We would need the coefficient of s squared to be equal to the coefficient of s squared in the original.
03:11
So we would need negative 2a minus 2b minus 3d equal to negative 4...