Question

$(a+b{)}^3=a^3+3xab+3a{b}^2+b^{2}y$.Then x+y is always

• A. a multiple of (a+b)
• B. a multiple of ab
• C. a prime number
• D. an even number

Answer 1

The correct option is A

a multiple of (a+b)

$(a+b{)}^3=a^3+3a^{2}b+3a{b}^2+b^3$
Comparing with the given expansion
$x=a$
$y=b$
$(x+y)=(a+b)$
So, we can say that (x +y) is a multiple of (a +b).