`a) [( 2 - 2^2 . 3 ) + ( 3^2 . 4 + 16 )] : 5`
`= [( 2 - 4 . 3 ) + ( 9 . 4 + 16 )] : 5`
`= [( 2 - 12 ) + ( 36 + 16 )] : 5`
`= [ -10 + 52 ] : 5`
`= 42 : 5 ( = 42/5 )`
`b) 107 - { 38 + [ 7 . 3^2 - 24 : 6 + ( 9 - 7 )^3]} : 15`
`= 107 - { 38 + [ 7 . 9 - 4 + 2^3 ]} : 15`
`= 107 - { 38 + [ 63 - 4 + 8 ]} : 15`
`= 107 - { 38 + 67 } : 15`
`= 107 - 105 : 15`
`= 107 - 7 ( = 100 )`
Tìm x :
`a) 128 - 3(x+4) = 2`
`-3(x+4) = 128 - 2`
`-3(x+4) = 126`
`x+4 = 126 : (-3)`
`x+4=-42`
`x = -42 - 4`
`x = -46`
`b) [(4x + 28).3 +55 ]:5 = 35`
`(4x + 28).3 +55 = 35 . 5`
`(4x + 28).3 +55 = 175`
`(4x + 28).3 = 175 - 55`
`(4x + 28).3 = 120`
`4x + 28 = 120 : 3`
`4x + 28 = 40`
`4x = 40 - 28`
`4x = 12`
`x = 12 : 4`
`x = 3`
`c) ( 12x - 4^3) . 8^3 = 4 . 8^4`
`12x - 4^3 = 4 . 8^4 : 8^3`
`12x - 4^3 = 4 . 8`
`12x - 4^3 = 32`
`12x = 32 + 64`
`12x = 96`
`x = 96 : 12`
`x = 8`
`d) 720 : [41 - (2x - 5)]=2^3 .5`
`720 : [41 - (2x - 5)]= 8 . 5`
`720 : [41 - (2x - 5)]= 40`
`41 - ( 2x - 5 ) = 720 : 40`
`41 - ( 2x - 5 ) = 18`
`-2x + 5 = 41 - 18`
`-2x + 5 = 23`
`-2x = 23 - 5`
`-2x = 18`
`x = 18 : (-2)`
`x = -9`
`e) 4x + 2x = 68 - 2^19 : 2^16`
`( 4 + 2 )x = 68 - 2^3`
`6x = 68 - 8`
`6x = 60`
`x = 60 : 6`
`x = 10`
`f) 9^(x-1) = 9`
`9^(x-1) = 9^1`
`x-1=1`
`x=1+1`
`x=2`
`g) x^4 - 1 = 15`
`x^4 = 15 + 1`
`x^4 = 16`
`x^4 = 2^4`
`x=2`
