số tự nhiên mà :)

\(x\in\left\{0;4;8;12;16;20;24;28;32;36;40;44;48\right\}\)

\(y\in\left\{1;2;4;13;26;52\right\}\)

\(\left(x+y\right)^2-\left(x-y\right)^2=\left(x+y+x-y\right)\left(x+y-x+y\right)=2x.2y=4xy\)

Chỉ được hỏi 1 câu mỗi lần thôi nhé !! Em hỏi bài mấy vậy??

Em ơi cj ko thấy câu hỏi nhé ^^

\(A=3+3^2+3^3+...+3^{2020}=3\left(1+3\right)+3^3\left(1+3\right)+...+3^{2019}.\left(1+3\right)=\left(1+3\right)\left(3+3^3+...+3^{2019}\right)=4.\left(3+3^3+...+3^{2019}\right)⋮4\)

\(\dfrac{2}{3}-\dfrac{1}{3}:x=\dfrac{4}{3}\)

\(\Rightarrow\dfrac{1}{3}:x=\dfrac{2}{3}-\dfrac{4}{3}=-\dfrac{2}{3}\)

\(\Rightarrow x=\dfrac{1}{3}:\dfrac{-2}{3}=\dfrac{1}{3}.\dfrac{-3}{2}=-\dfrac{1}{2}\)

\(3Fe_xO_y+2yAl\underrightarrow{t^0}3xFe+yAl_2O3\)