`1)`
`1)(123-145)-(23+55)`
`=123-145-23-55`
`=(123-23)+(-145-55)`
`=100-200=-100`
`2)(236-185)-(-85+36)`
`=236-185+85-36`
`=(236-36)+(-185+85)`
`=200-100=100`
`3)142-(150-249)-(249+42)`
`=142-150+249-249-42`
`=(142-42)-150+(249-249)`
`=100-150=-50`
`2)`
` 1)(x+3)^2=81`
` (x+3)^2=9^2`
` x+3=9`
` x=6`
`2)(2x-1)^4=625`
`(2x-1)^4=5^4`
`2x-1=5`
`2x=6`
`x=3`
`3)(x-5)^4=(x-5)^6`
`(x-5)^4-(x-5)^6=0`
`(x-5)^4[1-(x-5)^2]=0`
`<=>`\(\left[ \begin{array}{l}(x-5)^4=0\\1-(x-5)^2=0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x-5=0\\(x-5)^2=1\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=5\\\left[ \begin{array}{l}x-5=1\\x-5=-1\end{array} \right.⇔\left[ \begin{array}{l}x=6\\x=4\end{array} \right.\end{array} \right.\)
`=>x={4;5;6}`
