00:01
In this question, we are given this matrix i plus 2a inverse is given to be this matrix minus 1 ,245.
00:08
Now we have to use this to find the value of a.
00:12
We have to find the matrix a.
00:16
So for this, first of all, we know, say, a inverse, inverse of a inverse is going to be the matrix itself.
00:28
And inverse of a 2 cross 2 matrix, inverse of a 2 cross 2 matrix a, b, c, d is going to be 1 divided by ad minus b c, multiplied by d minus b, a.
00:47
So using this, therefore, we can say i plus 2a is going to be the inverse of the matrix minus 1, 24, 5.
00:59
Inverse of this is going to be the matrix i plus 2a.
01:02
Now using the formula, this will be 1 divided by minus 1 multiplied by 5, which is going to be minus 5, minus 2 multiplied by 4, which is going to be 8.
01:14
And here we will have 5 minus 1, minus 2 minus 4...