1: \(\dfrac{4}{23}+\dfrac{5}{21}+\dfrac{1}{2}-\dfrac{4}{23}+\dfrac{16}{21}\)

\(=1+\dfrac{1}{2}\)

\(=\dfrac{3}{2}\)

2: \(\left(\dfrac{1}{3}+\dfrac{12}{67}+\dfrac{13}{41}\right)-\left(\dfrac{79}{67}-\dfrac{28}{41}\right)\)

\(=\dfrac{1}{3}+\dfrac{12}{67}+\dfrac{13}{41}-\dfrac{79}{67}+\dfrac{28}{41}\)

\(=\dfrac{1}{3}\)

a: \(=12\cdot\dfrac{4}{9}+\dfrac{4}{3}=\dfrac{4}{3}\cdot4+\dfrac{4}{3}=\dfrac{4}{3}\cdot5=\dfrac{20}{3}\)

b: \(=\dfrac{-5}{7}\cdot\left(12.5+1.5\right)=\dfrac{-5}{7}\cdot14=-10\)

a) \(\frac{21}{47}+\frac{9}{45}+\frac{26}{47}+\frac{4}{5}\)

\(=\left(\frac{21}{47}+\frac{26}{47}\right)+\left(\frac{9}{45}+\frac{4}{5}\right)\)

\(=\frac{47}{47}+\left(\frac{1}{5}+\frac{4}{5}\right)\)

\(=1+1=2\)

b) \(12.\left(-\frac{2}{3}\right)^2+\frac{4}{3}\)

\(=12.\frac{4}{9}+\frac{4}{3}\)

\(=\frac{16}{3}+\frac{4}{3}\)

\(=\frac{20}{3}\)

c) \(12,5.\left(-\frac{5}{7}\right)+15.\left(-\frac{5}{7}\right)\)

\(=\left(-\frac{5}{7}\right).\left(12,5+15\right)\)

\(=\left(-\frac{5}{7}\right).27,5\)

\(=\left(-\frac{5}{7}\right).\frac{55}{2}\)

\(=-\frac{275}{14}\)

d) \(\frac{4}{5}.\left(\frac{7}{2}+\frac{1}{4}\right)^2\)

\(=\frac{4}{5}.\left(\frac{14}{4}+\frac{1}{4}\right)^2\)

\(=\frac{4}{5}.\left(\frac{15}{4}\right)^2\)

\(=\frac{4}{5}.\frac{225}{16}\)

\(=\frac{45}{4}\)

a)\(\frac{21}{47}+\frac{9}{45}+\frac{26}{47}+\frac{4}{5}\)

=\(\frac{21}{47}+\frac{1}{5}+\frac{26}{47}+\frac{4}{5}\)

=\(\left(\frac{21}{47}+\frac{26}{47}\right)+\left(\frac{1}{5}+\frac{4}{5}\right)\)

=\(\frac{47}{47}+\frac{5}{5}=1+1=2\)

b)\(12.\left(-\frac{2}{3}\right)^2+\frac{4}{3}\)

=\(12.\frac{4}{9}+\frac{4}{3}\)

=\(\frac{12}{1}.\frac{4}{9}+\frac{4}{3}=\frac{48}{9}+\frac{4}{3}\)

=\(\frac{16}{3}+\frac{4}{3}=\frac{20}{3}\)

c)\(12,5.\left(-\frac{5}{7}\right)+1,5.\left(-\frac{5}{7}\right)\)

=\(\left(-\frac{5}{7}\right).\left(12,5+1,5\right)\)

=\(\left(-\frac{5}{7}\right).14=\left(-\frac{5}{7}\right).\frac{14}{1}=-10\)

d)\(\frac{4}{5}.\left(\frac{7}{2}+\frac{1}{4}\right)^2\)

=\(\frac{4}{5}.\left(\frac{14}{4}+\frac{1}{4}\right)^2\)

=\(\frac{4}{5}.\left(\frac{15}{4}\right)^2\)

=\(\frac{4}{5}.\frac{225}{16}\)

=\(\frac{900}{80}=\frac{45}{4}\)

Nhớ tick cho mình nha!

2,5 x 7 = 17,5

4,18 x 5 = 20,9

0,52 x 1000 + 12,5 = 532,5

Tick mình

2,5x7=17,5

4,18x5=20,9

0,52x1000+12,5=532,5

a: x:3,2+3,6=9,6:1,2

=>x:3,2+3,6=8

=>x:3,2=8-3,6=4,4

=>\(x=4,4\cdot3,2=14,08\)

b: \(25,4+5x=313,5+4,4\)

=>\(5x+25,4=317,9\)

=>\(5x=317,9-25,4=292,5\)

=>\(x=\dfrac{292.5}{5}=58,5\)

c: \(12,5\cdot x-56,5=75,8\cdot2\)

=>\(x\cdot12,5-56,5=151,6\)

=>\(x\cdot12,5=151,6+56,5=208.1\)

=>\(x=\dfrac{208.1}{12.5}=16,648\)

d: \(3,84\cdot x-4,2=22,5:1,5\)

=>\(3,84x-4,2=15\)

=>3,84x=15+1,2=16,2

=>x=16,2/3,84=4,21875

e: 22,5*x=31,5*2,6

=>x*22,5=81,9

=>x=81,9/22,5=3,64

1: =-2/9(15/17+2/17)=-2/9

2: \(=\dfrac{-6}{3}+\dfrac{-21}{90}\)

=-2-7/30=-67/30

3: \(=\dfrac{3}{4}\cdot\dfrac{7}{5}+\dfrac{9}{7}\cdot\dfrac{3}{2}\)

=21/20+27/14=417/140

4: =-25/13(5/19+14/19)=-25/13

5: =-7/5-45/21=-7/5-15/7=-124/35

1: =-2/9(15/17+2/17)=-2/9

2: =34⋅75+97⋅32=34⋅75+97⋅32

=21/20+27/14=417/140

4: =-25/13(5/19+14/19)=-25/13

5: =-7/5-45/21=-7/5-15/7=-124/35

a) \(\dfrac{3}{4}\times x:\dfrac{1}{2}=\dfrac{4}{5}\)

\(\dfrac{3}{4}\times x=\dfrac{4}{5}\times\dfrac{1}{2}\)

\(\dfrac{3}{4}\times x=\dfrac{2}{5}\)

\(x=\dfrac{2}{5}:\dfrac{3}{4}\)

\(x=\dfrac{8}{15}\)

b) \(\left(14-x:6\right)\times7=84\)

\(14-x:6=84:7\)

\(14-x:6=12\)

\(x:6=14-12\)

\(x:6=2\)

\(x=6\times2=12\)

c) \(x\times1,5:2,4=0,3\)

\(x\times1,5=0,3\times2,4\)

\(x\times1,5=0,72\)

\(x=0,72:1,5\)

\(x=0,48\)

d) Thiếu x

Bài 1:

a)12,5 x (-5/7) + 1,5 x (-5/7)

=-5/7*(12,5+1,5)

=-5/7*14

=-10

b)(-1/4) x (6|2/11) + 3|9/11 x (-1/4)

=-1/4*(68/11+42/11)

=-1/4*10

=-5/2

c tương tự

d)\(\frac{9^8\cdot4^3}{27^4\cdot6^5}=\frac{\left(3^2\right)^8\cdot\left(2^2\right)^3}{\left(3^3\right)^4\cdot\left(2\cdot3\right)^5}=\frac{3^{16}\cdot2^6}{3^{12}\cdot2^5\cdot3^5}=\frac{3^{16}\cdot2^5\cdot2}{3^{16}\cdot3^1\cdot2^5}=\frac{2}{3}\)

Bài 2:

a)Ta có:

2⁸⁰⁰=(2⁸)¹⁰⁰=256¹⁰⁰

8²⁰⁰=(8²)¹⁰⁰=64¹⁰⁰

Vì 256¹⁰⁰>64¹⁰⁰ =>2⁸⁰⁰>8²⁰⁰

b)Ta có:

12⁴⁵=(12³)¹⁵=1728¹⁵

Vì 625¹⁵<1728¹⁵ =>625¹⁵<12⁴⁵

a) -5/7x(12,5+1,5)=-10

b) -1/4x (6I2/11+3I9/11) = -1/4x 10=-5/2

c) (-7/5 + -3/8 + -3/5+5/8): 2009/2010 = -7/4:2009/2010=-1005/574

d)3^16x 4^3/3^12x 6^5=3^4x4^3x6^5=......

bài 2)

2^800=2^4x200= 15^200> 8^200

=> 2^800>8^200

B) quên cách làm

dell   

bai o ban noi the co the ban la c ho day 

9: =3/2*5/12+3/16

=15/24+3/16

=5/8+3/16

=13/16