Đáp án:
`a)x=12`
`b)x=3`
`c)x=2`
`d)x=5`
Giải thích các bước giải:
`a)`
`12x=144`
`=>x=144:12`
`=>x=12`
`b)`
`2^x.16=128`
`=>2^x=128:16`
`=>2^x=8`
`=>2^x=2^3`
`=>x=3`
`c)`
`x^3=8`
`=>x^3=2^3`
`=>x=2`
`d)`
`(x-2)^2=9`
`=>`\(\left[ \begin{array}{l}(x-2)^2=3^2\\(x-2)^2=(-3)^2\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x-2=3\\x-2=-3\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=5\\x=-1\end{array} \right.\)
Vì `x∈NN`
`=>x∈{5}`