Hicc mình hông còn tgian mấy bạn giúp minh 2 câu thui cũng đc ạk

a)  5/9 + 4/9 . 3/7 + 4/9 . 4/7

  = 5/9 + 4/9 . (3/7 + 4/7)

  = 5/9 + 4/9 . 1

  = 5/9 + 4/9

  = 1 

mình lười nghĩ lắm sorry

\(\frac{3-\frac{3}{2}+\frac{3}{4}}{5-\frac{5}{2}+\frac{5}{4}}:\frac{6-\frac{6}{9}+\frac{6}{11}}{15-\frac{15}{9}+\frac{15}{11}}\)

\(=\frac{3\left(1-\frac{1}{2}+\frac{1}{4}\right)}{5\left(1-\frac{1}{2}+\frac{1}{4}\right)}:\frac{6\left(1-\frac{1}{9}+\frac{1}{11}\right)}{15\left(1-\frac{1}{9}+\frac{1}{11}\right)}\)

\(=\frac{3}{5}:\frac{6}{15}\)

\(=\frac{3}{5}:\frac{2}{5}=\frac{3}{5}\cdot\frac{5}{2}=\frac{3}{2}\)

3-3/2+3/4 =3x(1-1/2+1/4)

5-5/2+5/4   5x(1-1/2-1/4

rút gọn đi (1-1/2+1/4) là chỉ còn 3/5

câu dưới tương tự, kết quả là 6/15=2/5

a) -5/7.7/10 - 3/11 : 6/5

= -1/2 - 5/22

= -8/11

b) 5/14.1/3.-4/15:5/7

= -2/63:5/7 = -2/45

c) 2 13/15.11/15 - 13/15 + 2 13/15.4/15

= 2 13/15.(11/15 + 4/15) - 13/15

= 2 13/15.1 - 13/15

= 2 13/15 - 13/15

= 2

\(\dfrac{11}{6}+\dfrac{1}{4}=\dfrac{22}{12}+\dfrac{3}{12}=\dfrac{25}{12}\)

\(\dfrac{2}{5}-\dfrac{3}{8}=\dfrac{16}{40}-\dfrac{15}{40}=\dfrac{1}{40}\)

\(\dfrac{3}{10}-\dfrac{4}{15}=\dfrac{9}{30}-\dfrac{8}{30}=\dfrac{1}{30}\)

\(3+\dfrac{2}{5}=\dfrac{15}{5}+\dfrac{2}{5}=\dfrac{17}{5}\)

\(\dfrac{333}{777}+\dfrac{22}{55}=\dfrac{3}{7}+\dfrac{2}{5}=\dfrac{15}{35}+\dfrac{14}{35}=\dfrac{29}{35}\)

Lời giải:

\(\left(\frac{15}{\sqrt{6}+1}+\frac{4}{\sqrt{16}-2}-\frac{12}{3-\sqrt{16}}\right).(\sqrt{6}+11)=\left(\frac{15(\sqrt{6}-1)}{(\sqrt{6}+1)(\sqrt{6}-1)}+\frac{4}{4-2}-\frac{12}{3-4}\right)(\sqrt{6}+11)\)

\(=\left(\frac{15(\sqrt{6}-1)}{6-1}+2+12\right)(\sqrt{6}+11)=(3\sqrt{6}-3+14)(\sqrt{6}+11)\)

\(=(3\sqrt{6}+11)(\sqrt{6}+11)\)

1.a) 4.(12+88) = 4.100=400

b)7²- 6 .[2.8:8 ]=7²-6.[16:8]=7²-6 .2= 49-12=37  ( tui ko chắc lắm )

2.a) x=26-11=15 

b) (4x-15)³=5³ 

4x-15=5 

4x= 5+15

4x=20

vậy x = 20

Bài 2: 

a: Ta có: x+11=26

nên x=15

b: Ta có: \(\left(4x-15\right)^3=125\)

\(\Leftrightarrow4x-15=5\)

hay x=5

Giải:

a) \(11\dfrac{3}{4}.\left(6\dfrac{5}{6}-4\dfrac{1}{2}+1\dfrac{2}{3}\right)\) 

\(=\dfrac{47}{4}.\left(\dfrac{41}{6}-\dfrac{9}{2}+\dfrac{5}{3}\right)\) 

\(=\dfrac{47}{4}.4\) 

\(=47\) 

b) \(\left(5\dfrac{7}{8}-2\dfrac{1}{4}-0,5\right):2\dfrac{23}{26}\) 

\(=\left(\dfrac{47}{8}-\dfrac{9}{4}-\dfrac{1}{2}\right):\dfrac{75}{26}\) 

\(=\dfrac{25}{8}:\dfrac{75}{26}\) 

\(=\dfrac{13}{12}\)

c) \(\left(17\dfrac{13}{15}-3\dfrac{3}{7}\right)-\left(2\dfrac{12}{15}-4\right)\) 

\(=\dfrac{268}{15}-\dfrac{24}{7}-\dfrac{14}{5}+4\) 

\(=\left(\dfrac{268}{15}-\dfrac{14}{5}\right)+\left(\dfrac{-24}{7}+4\right)\) 

\(=\dfrac{226}{15}+\dfrac{4}{7}\) 

\(=\dfrac{1642}{105}\) 

d) \(2\dfrac{2}{3}.\left(\dfrac{-4}{5}.0,375.-10.\dfrac{-15}{24}\right)\) 

\(=\dfrac{8}{3}.\left(\dfrac{-4}{5}.\dfrac{3}{8}.-10.\dfrac{-5}{8}\right)\) 

\(=\left(\dfrac{8}{3}.\dfrac{3}{8}\right).\left(\dfrac{-4}{5}.\dfrac{-5}{8}.-10\right)\) 

\(=1.-5\) 

\(=-5\) 

Chúc bạn học tốt!

a,     (\(\dfrac{9}{10}\) - \(\dfrac{15}{16}\)) \(\times\) ( \(\dfrac{5}{12}\) - \(\dfrac{11}{15}\) - \(\dfrac{7}{20}\))

=  (\(\dfrac{72}{80}\) - \(\dfrac{75}{80}\))  \(\times\) (\(\)\(\dfrac{25}{60}\) - \(\dfrac{44}{60}\)  - \(\dfrac{21}{60}\))

= - \(\dfrac{3}{80}\)  \(\times\) (- \(\dfrac{2}{3}\))

= \(\dfrac{1}{40}\) 

b, (-1)³ + (- \(\dfrac{2}{3}\))² : 2\(\dfrac{2}{3}\) + \(\dfrac{5}{6}\)

=  -1³ +   \(\dfrac{4}{9}\) : \(\dfrac{8}{3}\) + \(\dfrac{5}{6}\)

= -1 + \(\dfrac{4}{9}\) \(\times\) \(\dfrac{3}{8}\) + \(\dfrac{5}{6}\)

= -1 + \(\dfrac{1}{6}\) + \(\dfrac{5}{6}\)
= -1 + 1

= 0

c, 15 \(\times\) (- \(\dfrac{1}{5}\))² + \(\dfrac{1}{5}\) - 2 \(\times\) (- \(\dfrac{1}{2}\))³ - \(\dfrac{1}{2}\)

= 15 \(\times\) \(\dfrac{1}{25}\) + \(\dfrac{1}{5}\) - 2 \(\times\) (- \(\dfrac{1}{8}\)) - \(\dfrac{1}{2}\)

=  \(\dfrac{3}{5}\)  + \(\dfrac{1}{5}\) + \(\dfrac{1}{4}\) - \(\dfrac{1}{2}\)

= \(\dfrac{4}{5}\) - \(\dfrac{1}{4}\)

= \(\dfrac{11}{20}\)