a) 20 × 190 × 50 = (20 × 50) × 190 = 1000 × 190

= 190000

b) (900 × 28) ÷ 9 = (900 ÷ 9) × 28 = 100 × 28 = 2800

\(900\times28:9\\ =\left(900:9\right)\times28\\ =100\times28\\ =2800\)

(900x28):9

=(900:9)x28

=100x28

=2800

126 : 3 + 231 : 3 + 543 : 3

= ( 126 + 231 + 543 ) : 3

= 900 : 3

= 300

126 : 3 + 231 : 3 + 543 : 3

= \(126.\frac{1}{3}+231.\frac{1}{3}+543.\frac{1}{3}\)

=\(\frac{1}{3}\left(126+231+543\right)=\frac{1}{3}.900=300\)

\((\frac{1}{2}+\frac{1}{4}+\frac{1}{6}) \)x \((\frac{36}{9}-\frac{12}{9}:\frac{1}{3}) \)

\(= (\frac{1}{2}+\frac{1}{4}+\frac{1}{6}) \) x \((\frac{36}{9}-\frac{36}{9})\)

\( = (\frac{1}{2}+\frac{1}{4}+\frac{1}{6}) \) x \(0\)

\(= 0\)

Hướng dẫn giải:

a.

17 x 543 + 83 x 543

= (17 + 83) x 543

= 100 x 543

= 54300

b.

318 x 963 + 682 x 963

= (318 + 682) x 963

= 1000 x 963

= 963000

a)17x543+83x543

=(17+83)x543

=100x543

=54300

b)318x963+682x963

=(318+682)x963

=1000x963

=963000

TL

1+2+3+4+5+6+7+8+9=45

nha bn

HT

1+2+3+...+9

=(1+9)+(2+8)+...+5

=10+10+...+5

=10.4+5

=45

HT

9/5 + 4/7 + 6/5 + 3/7

=  ( 9/5 + 6/5 ) + ( 4/7 + 3/7)

=            3        + 1

=        4

9/5 + 4/7 + 6/5 + 3/7 = (9/5 + 6/5) + (4/7 + 3/7)

= 15/5 + 7/7

= 3 + 1

= 4

1/2 x 45/33 x 1/9 x 11/6 = (1/2 x 1/9) x (45/33 x 11/6)

= 1/18 x 45/18

= 5/2

2/5+11/9+3/5+7/9= (2/5+3/5)+(11/9+7/9)                             = 1+2                             = 3

+1