00:01
In the question, we are given with the equation that is d square y upon dt square plus 4 dy by dt plus 20y will be equal to e to the power minus t cos t.
00:20
So, let d by dt be d.
00:27
So, we will have d square plus 4d plus 20 multiplied by y will be equal to e to the power minus t cos t.
00:40
So, now first we will write auxiliary equation.
00:47
So, we will have m square plus 4m plus 20 will be equal to 0.
01:01
Now, we can further write this is in the form that is m plus 2 whole square plus 16 is equal to 0.
01:13
So, from here we will have m plus 2 whole square will be equal to minus 16.
01:23
So, m plus 2 will be equal to under root of minus 16.
01:30
So, under root of minus 16 can be written as plus minus 4 eta...