LỚP 3     

k cho mk nhé

20^5:4^2:125=25.4^3

hok tốt

Câu 1: 

a: x+2,57=14,25-6,3

=>x+2,57=7,95

=>x=5,38

b: 12,9-x=4,2+2,4

=>12,9-x=6,6

hay x=6,3

a) \(18+25\times4-4^3\)

\(=18+100-64\)

\(=118-64\)

\(=54\)

b) \(275-\left(49+125\div5^3\right)\)

\(=275-\left(49+125\div125\right)\)

\(=275-\left(49+1\right)\)

\(=275-49-1\)

\(=226-1\)

\(=225\)

c) \(2015+\left(8\times15-\left(18-8\right)^2\right)\)

\(=2015+\left(8\times15-\left(10\right)^2\right)\)

\(=2015+\left(8\times15-100\right)\)

\(=2015+\left(120-100\right)\)

\(=2015+20\)

\(=2035\)

a, 165:11.999 + 85.999 = (15.11):11.999 + 85.999 = [(15.11):11].999 + 85.999

= 15.(11:11).999 + 85.999 = 15.999 + 85.999 = (15+85).999 = 99900

b, 25.4 + 25:5 – 4.(30 – 5) – 5 = 25.4 + 25:5 – 4.25 – 5 = (25.4 – 4.25) + (25:5 – 5) = 0 + 0 = 0

2,57 x 112 - 2,57 : 0,5 - 25,7

= 2,57.112-2,57.2-25,7

= 2,57.(112-57,2)-25,7

= 2,57.54,8 - 25,7

=140,836-25,7

=115,136

2,57 x 112 - 2,57 : 0,5 - 25,7

= 2,57 x 112 - 2,57 x 2 - 2,57 x 10

= 2,57 x ( 112 - 2 - 10 )

= 2,57 x 100 = 257