a 5. 4 ² - 18 ÷ 3 ³ b 3 ³ . 18- 3 ² . 12 c 39. 21 ³+ 87. 30 d 80- [ 130 - (12 - 4 ²) ] e 12 : { 390: [ 500 -(125+35 .7) ] }

Đáp án+Giải thích các bước giải:

 `a)``5.4^2-18:3^3`

`=``5.16-18:27`

`=``80-18:27`

`=``80-`$\dfrac{2}{3}$

`=`$\dfrac{238}{3}$

`b)` `3^3.18-3^2.12`

`=``27.18-9.12`

`=``486-108`

`=``378`

`c)` `39.21^3+87.30`

`=39.9261+2610`

`=361179+2610`

`=363789`

`d)` `80-[130-(12-4^2)]`

`=``80-[130-(-4)]`

`=80-134`

`=-54`

`e)``12:{390:[500-(125+35.7)]}`

`=12:{390:[500-270]}`

`=``12:{390:130}`

`=12:3`

`=4`

Đáp án+Giải thích các bước giải:

a )5. 4 ² - 18 ÷ 3³
=5.16-18:27
=80-$\frac{2}{3}$ 
=$\frac{238}{3}$ 
b) 3 ³ . 18- 3 ² . 12

=27.18-9.12
=486-108
=378
c 39. 21 ³+ 87. 30
=39.9261+87.30
=361179+2610
=358569
d 80- [ 130 - (12 - 4 ²) ]
=80-[130-(12-16)]
=80-[130-(-4)]
=80-(130+4)
=80-134
=-54
e 12 : { 390: [ 500 -(125+35 .7) ] }
=12:{390:[500-(125+245)]}
=12:[390:(500-370)]
=12:(390:130)
=12:3
=4