Question

How do you simplify `-3xy (2x - 7y) + 6xy (9xy (9y - 2x)`?

Answer 1

As below

Explanation:

`-3xy (2x - 7y) + 6xy (9xy (9y - 2x)`

`=> -3x^2y + 21xy^2 + (6xy (81xy^2 - 18x^2y`

`=> -3x^2y + 21xy^2 + 486 x^2y^3 - 108x^3y^2`

`=> 3x^2y (162y^2-1) - 3xy^2(36x^2 - 7)`