$\#phnn$
`\text{Câu 1:}`
`a)216:3+138`
`=72+138`
`=210.`
`b)23.25+23.75`
`=23.(25+75)`
`=23.100`
`=2300.`
`c)6.3^3-80:2^3`
`=2.3.3^3-8.10:2^3`
`=2.3^4-2^3.10:2^3`
`=2.3^4-1.10`
`=2.3^4-10`
`=2.3^4-2.5`
`=2.(3^4-5)`
`=2.(81-5)`
`=2.76`
`=152.`
`d)2.{880:[178-5.(25-14:2)]}`
`=2.{880:[178-5.(25-7)]}`
`=2.{880:[178-5.18]}`
`=2.{880:[178-90]}`
`=2.{880:88}`
`=2.10`
`=20.`
`e)180:{[76-2.(3^2-2^2)]-6}`
`=180:{[76-2.(9-4)]-6}`
`=180:{[76-2.5]-6}`
`=180:{[76-10]-6}`
`=180:{66-6}`
`=180:60`
`=3.`
`\text{Câu 2:}`
`a)x-31=83`
`<=>x=83+31`
`<=>x=114.`
`\text{Vậy x = 114.}`
`b)6.x+19=61`
`<=> 6x=61-19`
`<=>6x=42`
`<=>x=42/6`
`<=>x=7.`
`\text{Vậy x = 7.}`
`c)2.(x-138)=6^2`
`<=>2.(x-138)=36`
`<=>x-138=36/2`
`<=>x-138=18`
`<=>x=18+138`
`<=>x=156.`
`\text{Vậy x = 156.}`
`d)5x-9=42`
`<=>5x=42+9`
`<=>5x=51`
`<=>x=51/5`
`<=>x=10,2.`
`\text{Vậy x = 10,2.}`
`e)2^x=16`
`<=>2^x=2^4`
`=>x=4.`
`\text{Vậy x = 4.}`
