Question

Could you show me the workings of this?

Answer 1

`a=-15`

Explanation:

When adding matrices, simply add the elements in the same row and column of the terms to get the value of the element in the resulting sum matrix.

`( (2,-5),(4,1),(color(red)(-2),2))+((-2,7),(-7,2),(color(red)(-8),2))+((4,-4),(-7,-6),(color(red)(-5),4))`

`color(white)("XXX")=((2-2+4, -5+7-4),(4-7-7, 1+2-6),(color(red)(-2-8-5), 2+2+4))`

`color(white)("XXX")=((4,-2),(-10,-3),(color(red)(-15),8))`