\(A=\frac{4^{15}.5^{15}.3^{12}.5^{12}}{5^{28}.2^{14}.3^{14}.2^{15}}=\frac{2.2^{29}.5^{27}.3^{12}}{5.5^{27}.2^{29}.3^{12}.3^2}=\frac{2}{45}\)

\(A=\frac{20^{15}.15^{12}}{25^{14}.6^{14}.8^5}=\frac{\left(2^2.5\right)^{15}.\left(3.5\right)^{12}}{\left(5^2\right)^{14}.\left(2.3\right)^{14}.\left(2^3\right)^5}=\frac{\left(2^2\right)^{15}.5^{15}.3^{12}.5^{12}}{5^{28}.2^{14}.3^{14}.2^{15}}\)

=\(\frac{2^{30}.3^{12}.5^{15}.5^{12}}{5^{28}.3^{14}.2^{14}.2^{15}}=\frac{2^{30}.3^{12}.5^{27}}{5^{28}.3^{14}.2^{29}}=\frac{2}{5.3^2}=\frac{2}{45}\)

1a) 25 .8 - 12.5 + 272 :17 - 8

= 200 -  60 + 16 - 8

= 140+16-8

= 156 - 8

= 148

b) 125: 25 +14 - 142 : 71

= 5 + 14 - 2 

= 19 - 2 = 17

c) 13. 17 - 256: 16 + 14 : 7 - 1

= 221 - 16 + 2 - 1 

= 205 + 2 - 1 

= 207 - 1 = 206

d) 15 . 24 - 14 . 5 (145 : 5 - 27)

= 360 - 70 (29- 27)

= 360 - 70 . 2

= 360 - 140

= 220

2a) 37 + x = 55

               x= 55 - 37

               x = 18

b) x- 31 = 24

     x       = 24 + 31

     x        = 55

c) 21 (x-11) = 21

        x - 11   = 21 : 21

          x        = 1 +11

           x       = 12

d ) 9. (x - 29)= 0

           x - 29 = 0 :9

             x       = 29

e) (x - 1954) . 5 = 50

         x - 1954   = 50 : 5

          x             = 1964

f ) 30 . 60 - x = 30

        1800 - x   = 30

             x        = 1800 - 30

             x        = 1770

Viết mỏi tay quá huhuh

Cảm ơn nghen

thanks bn nhé

4/3

5/3

10/9

3

2/3

8/6=4/3

 25/15=5/3

90/81=10/9

 48/16=3

 8/12=2/3

4/3

5/3

10/9

 3/4

 2/3

\(2\sqrt{27}-\sqrt{\dfrac{16}{3}}-\sqrt{48}-\sqrt{8\dfrac{1}{3}}\)

\(=6\sqrt{3}-4\sqrt{\dfrac{1}{3}}-4\sqrt{3}-5\sqrt{\dfrac{1}{3}}\)

\(=2\sqrt{3}-9\sqrt{\dfrac{1}{3}}\)

\(=2\sqrt{3}-3\sqrt{9\cdot\dfrac{1}{3}}\)

\(=2\sqrt{3}-3\sqrt{3}\)

\(=-\sqrt{3}\)

________________________

\(\left(\sqrt{125}-\sqrt{12}-2\sqrt{5}\right)\left(3\sqrt{5}-\sqrt{3}+\sqrt{27}\right)\)

\(=\left(5\sqrt{5}-2\sqrt{3}-2\sqrt{5}\right)\left(3\sqrt{5}-\sqrt{3}+3\sqrt{3}\right)\)

\(=\left(3\sqrt{5}-2\sqrt{3}\right)\left(3\sqrt{5}+2\sqrt{3}\right)\)

\(=\left(3\sqrt{5}\right)^2-\left(2\sqrt{3}\right)^2\)

\(=15-12\)

\(=3\)

bạn viết lại đề câu a.

5+ 5 + 5 + 5+ 5 + 5 +5+ 5 + 5 +5=5x10=50

25 + 25 + 25 + 25 + 25 + 25 +25 + 25=25x8=200

45 + 45 + 45 + 45 + 15 + 15 + 15 + 15=(45x4)+(15x4)=180+60=240

5+ 5 + 5 + 5+ 5 + 5 +5+ 5 + 5 +5
= 5 x 10
= 50

25 + 25 + 25 + 25 + 25 + 25 +25 + 25
= 25 x 8
= 200

45 + 45 + 45 + 45 + 15 + 15 + 15 + 15
= 45 x 4 + 15 x 4
= 180 + 60
= 240

2 + 4 + 6 + 8 + 10 + 12 + 14 + 16 + 18
= (2 + 18) + (4 + 16) + (8 + 12) + (6 + 14) + 10
= 20 + 20 + 20 + 20 + 10 
= 20 x 4 + 10
= 80 + 10
= 90 

125 + 125 + 125 + 125 - 25 - 25 - 25 - 25 
= 4 x (125 - 25) 
= 4 x 100 
= 400
(Tick cho mk pls ^^)

giúp mik a.

 a) 8/12 + 9/27 x 4/7

= 2/3 + 1/3 x 4/7

= 2/3 + 4/21

= 18/21

= 6/7

b) 8/16 x 36/45 - 4/25

= 1/2 x 4/5 - 4/25

= 2/5 - 4/25

= 6/25

a) 2/3+ 1/3x 4/7

= 2/3 + 4/21

= 14/21+ 4/21

= 18/21 

= 6/7

b) 1/2x 4/5 - 4/25

= 2/5- 4/25

= 10/25 - 4/25

=6/25