What should be added to x2+xy+y2 to obtain 2x2+3xy?
Finding the term to be added to obtain the equation
Let S be the term which when added to x2+xy+y2 gives 2x2+3xy
⇒ S+x2+xy+y2=2x2+3xy
⇒ S=2x2+3xy-x2+xy+y2
⇒ S=2x2+3xy-x2-xy-y2
⇒ S=2x2-x2+3xy-xy-y2
⇒ S=x2+2xy-y2
Hence, x2+2xy-y2 is the term that needs to be added to x2+xy+y2 to obtain 2x2+3xy.
(a) What should be added to x2 + xy + y2 to obtain 2x2 + 3xy?
(b) What should be subtracted from 2a + 8b + 10 to get − 3a + 7b + 16?