Multiply and then verify:

-3x²y² and (x - 2y) for x = 1 and y = 2.

(-3x²y²) $\times$ (x - 2y)

= (-3x²y²) $\times$ x - (-3x²y²) $\times$ 2y

= (-3x⁽²⁺¹⁾y²) - (-6x²y⁽²⁺¹⁾)

= -3x³y² + 6x²y³

For x = 1 and y = 2

(-3x²y²) $\times$ (x - 2y) = -3x³y² + 6x²y³

Taking LHS:

(-3x²y²) $\times$ (x - 2y)

= (-3 x 1² x 2²) x (1 - 2 x 2)

= (-3 x 1 x 4) x (1 - 4)

= (-12) x (- 3)

= 36

Now, taking RHS:

-3x³y² + 6x²y³

= -3 x 1³ x 2² + 6 x 1² x 2³

= -3 x 1 x 4 + 6 x 1 x 8

= -12 + 48

= 36

Hence, LHS = RHS.