Question

Tìm số nguyên x biết: a)2(5-x)+5=1-3x

b) x-1/ x+1=8/9

Answer 1

a) <=> 10 - 2x + 5 = 1 - 3x

   <=>    -2x + 3x    = 1 - 10 - 5

   <=>      x             = -14

b) \(\Leftrightarrow\frac{x-1}{x+1}-\frac{8}{9}=0\)

    \(\Leftrightarrow\frac{9\left(x-1\right)-8\left(x+1\right)}{9\left(x+1\right)}=0\)

     \(\Leftrightarrow\frac{9x-9-8x-8}{9x+9}=0\)

     \(\Leftrightarrow\frac{x-17}{9x+9}=0\)

ĐK: 9x + 9 \(\ne\)0 => x \(\ne\)-1

     \(\Leftrightarrow x-17=0\)

     \(\Leftrightarrow x=17\)

Ps: Câu b không chắc lắm. 

Answer 2

phan b Vu Nhu Mai sai roi phai the nay moi dung

x-1/x+1=8/9

(x-1).9=(x+1).8

9x-9=8x+8

9x-8x=8+9

1x=17

x=17;1

x=17