Question

Expand the following (4/5d - 7e)2

Answer 1

Answer: $\dfrac{16d^2}{25}+49e^2-\dfrac{56de}{5}$

Step-by-step explanation:

Given

The expression is

$(\dfrac{4d}{5}-7e)^2$

Use identity $(a-b)^2=a^2+b^2-2ab$

Apply identity

$\Rightarrow \left( \dfrac{4d}{5}-7e\right)^2=\left( \dfrac{4d}{5}\right)^2+(7e)^2-2\times \left( \dfrac{4d}{5}\right)(7e)\\\\\Rightarrow \left( \dfrac{4d}{5}-7e\right)^2=\dfrac{16d^2}{25}+49e^2-\dfrac{56de}{5}$