Question

Find the following products and verify the result for x = -1, y = -2:

(x²y - 1)(3 - 2x²y)

Answer 1

x²y (3 – 2x²y) – 1 (3 – 2x²y)

= 3x²y- 2x⁴y² – 3 + 2x²y

= 2x⁴y² + 5x²y – 3

Putting x = -1 and y = -2, we have

= [(-1)² (-2) – 1] [3 – 2 (-1)² (-2) = [-2 (-1)⁴ (-2)² + 5 (-1)² (2) – 3]

= (-2 – 1) (3 + 4) = - 8 – 10 – 3

-21 = - 21

Therefore,

L.H.S = R.H.S

Hence, verified