Question

Dados A=x²+2xy+y²,B=3x²-2xy+4y² e C=3x²-y²,calcule:

a) A-B

b) A-C

c)A+B+C

Answer 1

a)

A-B = (x²+2xy+y²)-(3x²-2xy+4y²) = x²-3x²+2xy+2xy+y²-4y²
A-B = -2x²+4xy-3y² 

b)

A-C = (x²+2xy+y²)-(3x²-y²) = x²-3x²+2xy+y²+y² = -2x²+2xy+2y²
A-C = 2(-x²+xy+y²)

c) 

A+B+C = x²+2xy+y²+3x²-2xy+4y²+3x²-y² = 7x²+0+4y² = 7x²+4y²