On the problem of mathematical matrix.

The addition and subtraction of matrix are the addition and subtraction of corresponding elements of matrix. Multiply 2 in front of the matrix is put into the matrix, and each element of the matrix needs to be multiplied by 2.

According to this expression, four equations can be obtained from the equality of four elements in different positions of the matrix, but in fact we only need two equations.

Element in the first column of the second row (lower left corner)

3-(-4b)= 2 *( 1/2)，b=- 1。

Element in the second row and second column (lower right corner)

B+2a-3=2*2, and a=4 is obtained.

Above, please adopt.