Question

Expand the following. a) (3x+4y)whole square 3

Answer 1

$using \: the \: identity \\ {(x \ + y)}^{3} = {x}^{3} + {y}^{3} + 3xy(x + y) \\ substituting \: the \: values \\ {(3x)}^{3} + {(4y)}^{3} + (3 \times 3x \times 4y)(3x + 4y) \\ {27x}^{3} + {64y}^{3} + 24xy(3x + 4y) \\ {27x}^{3} + {64y}^{3} + {72x}^{2} y + {96xy}^{2}$
hope it will help