a) \(\dfrac{3}{7}-\dfrac{4}{11}-\dfrac{3}{7}\)

=\(\left(\dfrac{3}{7}-\dfrac{3}{7}\right)-\dfrac{4}{11}\)

\(=-\dfrac{4}{11}\)

b) \(-\dfrac{5}{11}+\dfrac{3}{8}-\dfrac{6}{11}\)

\(=\left(-\dfrac{5}{11}-\dfrac{6}{11}\right)+\dfrac{3}{8}\)

\(=-1+\dfrac{3}{8}=-\dfrac{8}{8}+\dfrac{3}{8}=-\dfrac{5}{8}\)

c) \(\dfrac{3}{4}-\dfrac{1}{3}-\dfrac{11}{4}\)

\(=\left(\dfrac{3}{4}-\dfrac{11}{4}\right)-\dfrac{1}{3}\)

\(=-2-\dfrac{1}{3}=-\dfrac{6}{3}-\dfrac{1}{3}=-\dfrac{7}{3}\)

`a, 3/7 -4/11-3/7`

`=(3/7-3/7)-4/11`

`= 0/7-4/11`

`= -4/11`

__

`b, -5/11 +3/8 -6/11`

`=(-5/11-6/11)+3/8`

`=-11/11 + 3/8`

`= -1+3/8`

`= -8/8+3/8`

`=- 5/8`

__

`c,3/4 -1/3-11/4`

`=(3/4-11/4)-1/3`

`= -8/4-1/3`

`=-2-1/3`

`= -6/3-1/3`

`=-7/3`

a) \(\dfrac{-5}{9}-\dfrac{4}{15}+\dfrac{2}{9}-\dfrac{11}{15}\)

\(=\left(\dfrac{-5}{9}+\dfrac{2}{9}\right)-\left(\dfrac{4}{15}+\dfrac{11}{15}\right)\)

\(=\dfrac{-3}{9}-\dfrac{15}{15}\)

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

\(=-\dfrac{4}{3}\)

b) \(\dfrac{-8}{13}-\dfrac{7}{16}+\dfrac{21}{13}-\dfrac{1}{6}\)

\(=\left(\dfrac{-8}{13}+\dfrac{21}{13}\right)-\dfrac{7}{16}-\dfrac{1}{6}\)

\(=\dfrac{13}{13}-\dfrac{29}{48}\)

\(=1-\dfrac{29}{48}\)

\(=\dfrac{19}{48}\)

c) \(\dfrac{-15}{25}-\dfrac{14}{21}+\dfrac{8}{5}-\dfrac{5}{3}\)

\(=\dfrac{-3}{5}-\dfrac{2}{3}+\dfrac{8}{5}-\dfrac{5}{3}\)

\(=\left(\dfrac{-3}{5}+\dfrac{8}{5}\right)-\left(\dfrac{2}{3}+\dfrac{5}{3}\right)\)

\(=\dfrac{5}{5}-\dfrac{7}{3}\)

\(=1-\dfrac{7}{3}\)

\(=-\dfrac{4}{3}\)

a: =-5/9+2/9-11/15-4/15

=-3/9-1

=-12/9=-4/3

b: =-8/13+21/13-7/16-1/6

=1-1/6-7/16

=5/6-7/16

=19/48

c: =-15/25+8/5-2/3-5/3

=-7/3+1

=-4/3

a) \(-\dfrac{5}{9}-\dfrac{4}{15}+\dfrac{2}{9}-\dfrac{11}{15}\)

\(=\left(-\dfrac{5}{9}+\dfrac{2}{9}\right)+\left(-\dfrac{4}{15}-\dfrac{11}{15}\right)\)

\(=-\dfrac{1}{3}-1=-\dfrac{4}{3}\)

b) \(-\dfrac{8}{13}-\dfrac{7}{16}+\dfrac{21}{13}-\dfrac{1}{16}\)(sửa đề)

\(=\left(-\dfrac{8}{13}+\dfrac{21}{13}\right)+\left(-\dfrac{7}{16}-\dfrac{1}{16}\right)\)

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

c) \(-\dfrac{15}{25}-\dfrac{14}{21}+\dfrac{8}{5}-\dfrac{5}{3}\)

\(=-\dfrac{3}{5}-\dfrac{2}{3}+\dfrac{8}{5}-\dfrac{5}{3}\)

\(=\left(-\dfrac{3}{5}+\dfrac{8}{5}\right)-\left(\dfrac{2}{3}+\dfrac{5}{3}\right)\)

\(=1-\dfrac{7}{3}=\dfrac{-4}{3}\)

bạn chép hẳn đề ra mk làm cho chứ bn ghi tắt quá

So sánh hả bạn?

a,Dùng tính chất phần hơn ta có:

a+1/a=1+1/a                                   a+3/a+2=1+1/a+2

Vì 1/a>1/a+2 =>a+1/a >a+3/a+2

b,Dùng tính chất phần bù ta có:

1-a/a+6=6/a+6                                 1-a+1/a+7=6/a+7

Vì 6/a+6>6/a+7 =>a/a+6<a+1/a+7

nó không cho a = bao nhiêu à?:)

help me 

Bn tham khảo

hdsghj

Bài 1 :

a) \(...=5^5:5^4=5\)

b) \(...=7^8:7^9=\dfrac{1}{7}\)

c) \(...=2^{15}:\left(2^6.2^5\right)=2^{15}:2^{11}=2^4=16\)

d) \(...=3^{28}:3^{26}=3^2=9\)

Bài 2 :

a) \(...=3^2.3^3:3^4=3^5:3^4=3\)

b) \(...=10^9-10^9=0\)

c) \(...=5^{10}.5^{30}:5^{12}=5^{40}:5^{12}=5^{28}\)

d) \(...=5^{12}:5^9=5^3=125\)

`@` `\text {Ans}`

`\downarrow`

`1/3+6/9+4/5+5/25`

`= 1/3+2/3+4/5+1/5`

`= 1+1`

`= 2`

`4/7*2/5+4/7*3/5-1/7`

`= 4/7*(2/5+3/5)-1/7`

`= 4/7*1-1/7`

`= 4/7-1/7=3/7`

.....................................................