a) 45,5 x 21 + 54,5 x 21

= 21 x (45,5 + 54,5)

= 21 x 100

= 2100

b) 145,5 x 5,09 - 33,5 x 5,09 - 12 x 5,09

= 5,09 x (145,5 - 33,5 - 12)

= 5,09 x 100

= 509

a)45,5x21+54,5x21

=21x(45,5+54,5)

=21x100

=2100

b)154,5 x 5,09 - 33,5 x 5,09 -12 x 5,09 

=5,09 x(154,5 - 33,5 - 12)

=5,09 x 100

=509

45,5 x 21 + 54,5 x 21 = ( 45,5+54,5)x 21 = 100x21=2100

45,5 * 21+54,5 *21=(45,5+54,5)*21=100*21=2100

145,5*5,09-33,5*5,09-12*5,09=(145,5-33,5-12)*5,09=100*5,09=509

a. 100.23x23.5+100.23x76.5 = (76.5+23.5)x100.23=10023

a, 100,23*(23,5+76,5)=10023

b,45,5*100-455=4095

tk mình nha

a) 100,23x23,5+100,23x76,5

= 100,23x (23,5+76,5)

= 100,23 x 100

= 10023

b) 45,5x (45,5+54,5) - 455

= 45,5x 100 -455

= 4550 - 455

= 4095

45,5 * 21 + 54,5 *21

= 21 (45,5 + 54,5)

= 21 *100

= 2100

HT

@Sophia

45,5 x 21 +54,5 x 21

=(45,5 +54,5) x 21

=100 x 21 

=2100

=72140.25 nha

XIN đấy tích đi mà

HT

\(a,=69,78\times\left(\dfrac{3}{4}+\dfrac{1}{4}+99\right)\\ =69,78\times\left(\dfrac{4}{4}+99\right)\\ =69,78\times\left(1+99\right)=69,78\times100=6978\\ b,34,1\times8+34,1\times0,5\\ =34,1\times\left(8+0,5\right)\\ =34,1\times8,5\\ =289,85\)

a: =69,78(3/4+1/4+99)

=69,78*100

=6978

b: =34,1(8+0,5)=34,1*8,5=289,85

a.\(69,78\times\dfrac{3}{4}+69,78\times\dfrac{1}{4}+69,78\times99=69,78\times\left(\dfrac{3}{4}+\dfrac{1}{4}+99\right)=69,78\times100=6978\)

b. \(34,1\times8+34,1\times0,5=34,1\times\left(8+0,5\right)=34,1\times8,5=289,85\)

(96 ÷ 0,5 - 30 ÷ 0,2 - 84 × 0,5) × (45,5 × 2,98 × 13,4 × 50,04)

= (96 × 2 - 30 × 5 - 84 ÷ 2) × ("viết lại")

= (192 - 150 - 42) × (...)

= (42 - 42) × (...)

= 0 × (...)

= 0

thu oi

bạn ni cũng hỏi cai nay hả

\(\frac{1}{10}+\frac{2}{20}+\frac{3}{30}+\frac{4}{40}+\frac{5}{50}+\frac{6}{60}+\frac{7}{70}+\frac{8}{80}+\frac{9}{90}\)

\(=\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}\)

\(=\frac{9}{10}\)

1/10=1/10 ; 2/20=1/10 .......9/90=1/10

1/10*10 =10/10=1

Rút gọn ta đc:

\(\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}\)\(\frac{1}{10}\)

=\(\frac{1}{10}\)x9=\(\frac{9}{10}\)