Question

If `[(x + y, 7),(9, x - y)] = [(2, 7),(9, 4)]`, then x · y = ______.

Answer 1

If `[(x + y, 7),(9, x - y)] = [(2, 7),(9, 4)]`, then x · y = –3.

Explanation:

`[(x + y, 7),(9, x - y)] = [(2, 7),(9, 4)]`

Here x + y = 2   ...(i)

And x – y = 4   ...(ii)

On solving equation (i) and equation (ii)

x = 3

And y = –1

Now, x.y = (3).(–1)

= –3