Question

СРОЧНО АЛГЕБРА ЯКЛАСС

Answer 1

$\boxed{(a-b)(a+b)=a^2-b^2\;\;;\;\bigg(\dfrac{a}{b}\bigg)^n=\dfrac{a^n}{b^n}\;\;;\;\;(ab)^n=a^nb^n}\\\\\\\bigg(\dfrac{1}{2}x-\dfrac{4}{5}y\bigg)\cdot\bigg(\dfrac{1}{2}x+\dfrac{4}{5}y\bigg)=\bigg(\dfrac{1}{2}x\bigg)^2-\bigg(\dfrac{4}{5}y\bigg)^2=\dfrac{1^2}{2^2}x^2-\dfrac{4^2}{5^2}y^2=\boxed{\boxed{\dfrac{1}{4}x^2-\dfrac{16}{25}y^2}}$