Giải thích các bước giải:
`a,-11x+14(x+2)=34`
`=>-11x+14x+28=34`
`=>x(-11+14)=34-28`
`=>x3=6`
`=>x=6:3`
`=>x=2`
`b)5(x+2)+2(x+4)=25`
`=>5x+10+2x+8=25`
`=>x7+18=25`
`=>x7=25-18`
`=>x7=7`
`=>x=7:7`
`=>x=1`
`c)|x+3|=|5-14|`
`=>|x+3|=9`
`=>`\(\left[ \begin{array}{l}x+3=9\\x+3=-9\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=6\\x=-12\end{array} \right.\)
`d,3.|x+9|=21`
`=>|x+9|=21:3`
`=>|x+9|=7`
`=>`\(\left[ \begin{array}{l}x+9=7\\x+9=-7\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=-2\\x=-16\end{array} \right.\)
