Question

Solve the following :

If A = `[(2, 5),(3, 7)], "B" = 4[(1, 7),(-3, 0)]`, find matrix A – 4B + 7I, where I is the unit matrix of order 2.

Answer 1

A – 4B + 7I = `[(2, 5),(3, 7)] - 4[(1, 7),(-3, 0)] + 7[(1, 0),(0, 1)]`

= `[(2, 5),(3, 7)] - [(4, 28),(-12, 0)] + [(7, 0),(0, 7)]`

= `[(2 - 4 + 7, 5 - 28 + 0),(3 + 12 + 0, 7 - 0 + 7)]`

= `[(5, -23),(15, 14)]`.