Question

Subtract:

−11x²y² + 7xy −6 from 9x²y² −6xy + 9

Answer 1

Change the sign of the term of the expression that is to be subtracted and then add.

Term to be subtracted = −11x²y² + 7xy −6
Changing the sign of each term of the expression gives 11x²y² -7xy +6.
On adding:
(9x²y² −6xy + 9)+(11x²y² -7xy +6) = 9x²y² −6xy + 9+11x²y² -7xy +6
= (9+11)x²y² (-7−6)xy + 15
= 20x²y² −13xy +15