Question

The expansion of (x+2y)${}^2$ is:

• A. 4x${}^2$ + 4xy + 4y${}^2$
• B. x${}^2$ + 4xy + 4y${}^2$
• C. x${}^2$ + 14xy + 4y${}^2$
• D. x${}^2$ + 4xy + 16y${}^2$

Answer 1

The correct option is B x${}^2$ + 4xy + 4y${}^2$

Using the identity (a+b)${}^2$ = a${}^2$ + 2ab + b${}^2$
(x+2y)${}^2$ = x${}^2$ + 2(x)(2y) + (2y)${}^2$ = x${}^2$ + 4xy + 4y${}^2$.