nhưng vẫn ko có mà

tôi bt bạn giỏi rồi

c) x²+y²=(x+y)²\(-2xy\)

\(\Rightarrow x^2+y^2+2xy=\left(x+y\right)^2\)

\(\Rightarrow\left(x+y\right)^2=VP\left(đpcm\right)\)

oki

 làm gì có pt đó đâu

d)\(\dfrac{x+7}{8}=\dfrac{63}{24}\Rightarrow x+7=\dfrac{8.63}{24}=21\\ \Rightarrow x=21-7=14\)

c)\(\dfrac{x-5}{7}=\dfrac{6}{21}\Rightarrow x-5=\dfrac{6.7}{21}=2\Rightarrow x=2+5=7\)

b)\(\dfrac{2}{5}=\dfrac{12}{x}\Rightarrow x=\dfrac{5.12}{2}=30\)

a)\(\dfrac{x}{60}=\dfrac{-3}{4}\Rightarrow x=\dfrac{-3.60}{4}=-45\)

Fe_xO_y   +   yH₂    → xFeO    +  yH₂O