Question

If A = `[(sec60°, cos90°),(-3tan45°, sin90°)] and "B" = [(0, cos45°),(-2, 3sin90°)]` Find : 2A – 3B

Answer 1

Given
A = `[(sec60°, cos90°),(-3tan45°, sin90°)]`
and
B = `[(0, cos45°),(-2, 3sin90°)]`

A = `[(sec60° , cos90°),(-3tan45°, sin90°)] = [(2, 0),(3, 1)]`   ...(∵  sec60° = 2, cos90° = 0, tan45° = 1, sin90° = 1)

B = `[(0, cos45°),(-2, 3sin90°)] = [(0, 1),(-2, 3)]` ...(∵ cot45° = 1)
2A – 3B
= `2[(2, 0),(3, 1)] -3[(0, 1),(2, 3)]`

= `[(4, 0),(6, 2)] - [(0, 3),(-6, 9)]`

= `[(4 - 0, 0 - 3),(-6 + 6, 2 - 9)]`

= `[(4, -3),(0, -7)]`.