Question

20 (7x2+3y)2 in expanded form is equal to _____.


a.
49x2+42x2y+9y


b.
None of these


c.
49x4+9y2


d.
14x4+6y2

Answer 1

$\underline{\textbf{Given:}}$

$\mathsf{(7x^2+3y)^2}$

$\underline{\textbf{To find:}}$

$\mathsf{Expanded\;form\;of\;(7x^2+3y)^2}$

$\underline{\textbf{Solution:}}$

$\underline{\textsf{Formula used:}}$

$\boxed{\mathsf{(a+b)^2=a^2+b^2+2ab}}$

$\mathsf{Consider,}$

$\mathsf{(7x^2+3y)^2}$

$\textsf{using the above identity,}$

$\mathsf{=(7x^2)^2+(3y)^2+2(7x^2)(3y)}$

$\mathsf{=49x^4+9y^2+42\,x^2y}$

$\implies\boxed{\mathsf{(7x^2+3y)^2=49x^4+9y^2+42\,x^2y}}$

$\underline{\textbf{Answer:}}$

$\textsf{Option (a) is correct}$

$\underline{\textbf{Find more:}}$

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