Question

from the sum of X² + 3xy + 8y² and 2x²-9xy-3y² subtract the sum of 3x²-11xy+7y²and 2x²+5xy-3y².​

Answer 1

Solution,

X² + 3xy + 8y²

+ 2x²-9xy-3y²

-----------------------

3x² -3xy-5y²

Again,

3x²-11xy+7y²

+2x²+5xy-3y²

-----------------------

5x²-6xy+4y²

Now subtracting the sum,

3x² -3xy-5y²

5x²-6xy+4y²

- + -

--------------------

-2x²+3xy-9 y²

Answer 2

First, adding 3x2+5xy+7y2+3 and 2x2−4xy−3y2+7, we have 

= 3x2+5xy+7y2+3+2x2−4xy−3y2+7 

= 5x2+xy+4y2+10 

Now, 

Subtracting 5x2+xy+4y2+10 from 9x2−8xy+11y2 

= (9x2−8xy+11y2)−(5x2+xy+4y2+10) 

= 9x2−8xy+11y2−5x2−xy−4y2−10 

= 4x2−9xy+7y2−10