Question

Tìm số nguyên y thoả mãn \(\frac{y+5}{7-y}=\frac{2}{-5}\)là

Answer 1

\(\frac{y+5}{7-y}=\frac{2}{-5}\)

<=>(y+5).(-5)=(7-y).2

<=>(-5y)+(-25)=14-2y

<=>(-5y+2y)=25+14

<=>(-3y)=39

<=>y=-13

Vậy y=-13

Answer 2

\(\Leftrightarrow\frac{y+5}{7-y}=\frac{-y+5}{y-7}\)

\(\Leftrightarrow\frac{-y+5}{y-7}=\frac{-2}{5}\)

\(\Rightarrow\frac{y}{7-y}+\frac{5}{7-y}=\frac{-2}{5}\)

\(\Leftrightarrow\frac{y}{7-y}+\frac{5}{7-y}+\frac{2}{5}=0\)

\(\Rightarrow\frac{-3\left(y+13\right)}{5\left(y-7\right)}=0\)

\(\Leftrightarrow\frac{1}{y-7}=0\)

=>y=13

Answer 3

chêt nhầm y=-13 ms đúng

Answer 4

-5(y+5)=2(7-y)=>-5y-25=14-2y=>-5y+2y=39=>-3y=39=>y=-13