Bài 1:
a) `27 × 75 + 25 × 27 - 250`
`= 27 × ( 75 + 25 ) - 250`
`= 27 × 100 - 250`
`= 2700 - 250`
`= 2450`
b) `12 : { 390 : [ 500 - ( 125 + 35 × 7 )]}`
`= 12 : ( 390 : [ 500 - ( 125 + 245 )]}`
`= 12 : [ 390 : ( 500 - 370 )]`
`= 12 : ( 390 : 130 )`
`= 12 : 3`
`= 4`
c) `39 × 213 + 87 × 39`
`= 39 × ( 213 + 87 )`
`= 39 × 300`
`= 11700`
`d) `2 × 5^3 - 36 : 3^2`
`= 2 × 125 - 36 : 9`
`= 250 - 4`
`= 246`
e) `3^3 × 18 - 3^3 × 12`
`= 27 × 18 - 27 × 12`
`= 27 × ( 18 - 12 )`
`= 27 × 6`
`= 162`
Bài 2:
a) `11^5 : 11^2 = 11^( 5 + 2 ) = 11^7`
b) `5^5 : 5^2 : 5 = 5^( 5 + 2 + 1 ) = 5^8`
c) `3^4 × 3^3 × 3^2 = 3^( 4 + 3 + 2 ) = 3^9`
d) `16^2 : 4^2 = ( 4 × 4 )^2 : 4^2 = 4^2 × 4^2 : 4^2 = 4^( 2 + 2 - 2 ) = 4^2`
e) `25^2 : 5^2 = ( 5 × 5 )^2 : 5^2 = 5^2 × 5^2 : 5^2 = 5^( 2 + 2 - 2 ) = 5^2`
Bài 3:
a) `541 + ( 218 - x ) = 735`
`218 - x = 735 - 541`
`218 - x = 194`
`x = 218 - 194`
`x = 24`
b) `5 × ( x + 35 ) = 515`
`x + 35 = 515 : 5`
`x + 35 = 103`
`x = 103 - 35`
`x = 68`
c) `96 - 3 × ( x + 1 ) = 42`
`3 × ( x + 1 ) = 96 - 42`
`3 × ( x + 1 ) = 54`
`x + 1 = 54 : 3`
`x + 1 = 18`
`x = 18 - 1`
`x = 17`
d) `12 × x - 33 = 3`
`12 × x = 3 + 33`
`12 × x = 36`
`x = 36 : 12`
`x = 3`
@ Rin
