Question

mọi người giúp mình với ạ

Answer 1

`a)|5x+6|=9`

`@TH1:5x+6=9<=>5x=3<=>x=3/5`

`@TH2:5x+6=-9<=>5x=-15<=>x=-3`

______________________________________

`b)[2x+1]/[1-x]=-5/3`        `ĐK: x \ne 1`

`<=>3(2x+1)=-5(1-x)`

`<=>6x+3=-5+5x`

`<=>x=-8` (t/m)

___________________________________________

`c)x/4=y/3=>x=4/3y`

Thay `x=4/3y;z=2y` vào `x-y+z=22` có:

   `4/3y-y+2y=22`

`<=>7/3y=22<=>y=66/7`

    `->{(x=4/3 . 66/7=88/7),(z=2. 66/7=132/7):}`

Answer 2

\(\left|5x+6\right|=9\)

\(Th1:\left|5x+6\right|=\left|-9\right|\)

=>\(5x+6=-9\)

=>\(5x=-9-6\)

=>\(5x=-15\)

=>\(x=-15:5\)

=>x=-3

\(Th2:\left|5x+6\right|=\left|9\right|\)

=>\(5x+6=9\)

=>\(5x=9-6\)

=>\(5x=3\)

=>\(x=5:3\)

=>\(x=\dfrac{5}{3}\)