Question

Answer 1

B3:

\(\Rightarrow\dfrac{21}{x+1}-\dfrac{2y-5}{14}=\dfrac{7}{2}\)

<=> \(\dfrac{21.7.2}{7.2\left(x+1\right)}-\dfrac{\left(2y-5\right)\left(x+1\right)}{7.2\left(x+1\right)}-\dfrac{7.7\left(x+1\right)}{2.7.\left(x+1\right)}=0\)

<=> \(\dfrac{294}{....}-\dfrac{2xy+2y-5x-5}{....}-\dfrac{49x+49}{...}=0\)

<=> \(294-2xy-2y+5x+5-49x-49=0\)

<=> \(250-2xy-2y-44x=0\)

lạ quá:v

Answer 2

Bài 1: 

ƯCLN(80;46)=2

BCNN(28;60)=420