Đáp án `+`Giải thích các bước giải:
` a) 2x - 12.4 = 28`
`-> 2x - 48 = 28`
`-> 2x = 28+48 = 76`
`-> x = 76 : 2 = 38 `
` b) 128 - 3(x+4) = 23`
`-> 3(x+4) = 128 - 23 = 105`
`-> x+4 = 105:3 = 35`
`-> x = 35-4=31`
` c) 20 +8.(x+3) = 5^2 . 4`
`-> 20 + 8(x+3) = 100`
`-> 8(x+3) = 100-20=80`
`-> x+3 = 80:8=10`
` -> x = 10 - 3 = 7`
` d) (12x - 4^3) . 8^3 = 4.8^4`
`-> 12x - 4^3 = 4.8^4 : 8^3 `
`-> 12x - 4^3 = 4.8 = 32`
`-> 12x = 32 + 4^3 = 96`
`-> x = 96 : 12 = 8`
` e) 720 : [41 - (2x -5)] = 2^3 . 5`
`-> 720 : [41 - (2x - 5)] = 40 `
`-> 41 - (2x - 5) = 720 : 40 = 18`
`-> 2x - 5 = 41 - 18 = 23`
`-> 2x = 23 + 5 = 28`
`-> x = 28 : 2 = 14`
` f) (2x -4)(x-3) = 0`
` ->` \(\left[ \begin{array}{l}2x-4=0\\x-3=0\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x = 2\\x=3\end{array} \right.\)
` g) (2x + 1)^3 = 5.25`
`-> (2x+1)^3 = 125=5^3`
`-> 2x + 1 = 5`
`-> 2x = 5-1=4`
`-> x= 4:2=2`
` h) 2^x . 4 = 128`
`-> 2^x = 128:4 = 32 = 2^5`
`-> x=5`
` i) 5^(x-2) = 1`
`-> 5^(x-2) = 5^0`
`-> x-2=0`
`-> x= 0+2=2`
` k) 2^x+ 2^(x+3) = 144`
`-> 2^x + 2^x . 2^3 =144`
`-> 2^x .(1 + 2^3) = 144`
`-> 2^x . 9 = 144`
`-> 2^x =144 : 9 = 16 = 2^4`
`-> x=4`
