a) 

\(=\frac{3}{5}.\frac{3}{7}+\frac{3}{5}.\frac{4}{7}-\left(1+\frac{3}{5}\right)\)

\(=\frac{3}{5}\left(\frac{3}{7}+\frac{4}{7}\right)-1-\frac{3}{5}\)

\(=\frac{3}{5}-1-\frac{3}{5}\)

\(=-1\)

b) \(=\frac{2^2.5.7.5^2.7^3}{2^2.5^2.7^{2.2}}\)

\(=\frac{2^2.5^{1+2}.7^{3+1}}{2^2.5^2.7^4}=\frac{2^2.5^3.7^4}{2^2.5^2.7^4}=2^{2-2}.5^{3-2}.7^{4-4}=2^0.5^1.7^0=1.5.1=5\)

b)\(\left(2016.1017+2017.2018\right).\left(1+\frac{1}{2}:\frac{3}{2}-\frac{4}{3}\right)\)

\(\left(2016.2017+2017.2018\right)\left(1+\frac{1}{3}-\frac{4}{3}\right)\)

\(\left(2016.2017+2017.2018\right).\left(\frac{4}{3}-\frac{4}{3}\right)\)

\(\left(2016.2017+2017.2018\right).0\)

\(=0\)

a) \(1001.789+456.128.128-789+912.436\)

\(=\left(1001.789-789\right)+\left(456.2.64.128+912.436\right)\)

\(=789.1000+912.4\left(2048+109\right)\)

\(=789000+912.4.2157\)

\(=8657736\)

c)\(5\frac{9}{10}+\frac{3}{2}-\left(2\frac{1}{3}.4\frac{1}{2}-2.2\frac{1}{3}\right):\frac{7}{4}\)

\(=\frac{59}{10}+\frac{3}{2}-\left(\frac{7}{3}.\frac{9}{2}-2.\frac{7}{3}\right):\frac{7}{4}\)

\(=\frac{59}{10}+\frac{3}{2}-\left[\frac{7}{3}\left(\frac{9}{2}-2\right)\right]:\frac{7}{4}\)

\(=\frac{59}{10}+\frac{3}{2}-\left(\frac{7}{3}.\frac{5}{2}\right):\frac{7}{4}\)

\(=59+\frac{3}{2}-\frac{35}{6}.\frac{4}{7}\)

\(=\frac{59}{10}+\frac{3}{2}-\frac{10}{3}\)

\(=\frac{177+45-100}{30}=\frac{122}{30}=\frac{61}{15}\)

Bài 1 :

\(\left(\frac{1}{8}+\frac{1}{8.15}+\frac{1}{15.22}+...+\frac{1}{43.50}\right)\frac{4-3-5-7-...-49}{217}\)

\(=\frac{1}{7}\left(1-\frac{1}{8}+\frac{1}{8}-\frac{1}{15}+\frac{1}{15}-\frac{1}{22}+...+\frac{1}{43}-\frac{1}{50}\right).\frac{5-\left(1+3+5+7+...+49\right)}{217}\)

\(=\frac{1}{7}\left(1-\frac{1}{50}\right).\frac{5-\left(12.50\right)+25}{217}\)

\(=\frac{1}{7}.\frac{49}{50}.\frac{5-625}{217}\)

\(=\frac{-2}{5}\)

Bài 2 :

\(B=\frac{x^2+17}{x^2+7}=\frac{\left(x^2+7\right)+10}{x^2+7}=1+\frac{10}{x^2+7}\)

Ta có : \(x^2\ge0\). Dấu '' = '' xảy ra khi :

\(x=0\Rightarrow x^2+7\ge7\)( 2 vế dương )

\(\Rightarrow\frac{10}{x^2+7}\le\frac{10}{7}\)

\(\Rightarrow1+\frac{10}{x^2+7}\le1+\frac{10}{7}\)

\(\Rightarrow B\le\frac{17}{7}\)

Dấu '' = '' xảy ra < = > x = 0

Vậy Max \(B=\frac{17}{7}\Leftrightarrow x=0\) 

đáp án :19/12

Số cây cam là:
120 : ( 2 + 3 ) x 2 = 48 (cây)
Số cây xoài là:
( 1 + 5 ) = 20 ( cây )
Số cây chanh là:
120 - ( 48 + 20 ) = 52 ( cây )
               Đáp số : cam : 48 cây
                            xoài : 20 cây
                            chanh : 52 cây.

ai trên 10 điểm thì mình nha

\(=\frac{-1}{4}+\frac{7}{33}-\frac{5}{3}-\left(-\frac{5}{4}\right)-\frac{6}{11}+\frac{48}{49}\)\(\frac{48}{49}\)

\(=\frac{-1}{4}+\frac{7}{33}-\frac{5}{3}+\frac{5}{4}-\frac{18}{33}+\frac{48}{49}\)

\(=\left(\frac{-1}{4}+\frac{5}{4}\right)+\left(\frac{7}{33}-\frac{18}{33}\right)-\frac{5}{3}\)\(+\frac{48}{48}\)

\(=1+\frac{-1}{3}-\frac{5}{3}+\frac{48}{49}\)

\(=1+\left(-2\right)+\frac{48}{49}\)

\(=-1+\frac{48}{49}\)

\(=\frac{-49}{49}+\frac{48}{49}\)

\(=\frac{-1}{49}\)

Bước đến nhà em bóng xế tà

Đứng chờ năm phút bố em ra

Lơ thơ phía trước vài con chó

Lác đác đằng sau chiếc chổi chà

Sợ quá anh chuồn quên đôi dép

Bố nàng ngoác mỏ đứng chửi cha

Phen này nhất quyết thuê cây kiếm

Trở về chém ổng đứt làm ba

\(E=\frac{0,8:\left(\frac{4}{5}.1,25\right)}{0,64-\frac{1}{25}}+\frac{\left(1,08-\frac{2}{25}\right):\frac{4}{7}}{\left(6\frac{5}{9}-3\frac{1}{4}\right).2\frac{2}{17}}+\left(1,2.0,5\right):\frac{4}{5}\)

\(E=\frac{\frac{4}{5}:\frac{4}{5}:1,25}{\frac{16}{25}-\frac{1}{25}}+\frac{\left(\frac{27}{25}-\frac{2}{25}\right).\frac{7}{4}}{\left(\frac{59}{9}-\frac{13}{4}\right).\frac{36}{17}}+\frac{6}{5}.\frac{1}{2}.\frac{5}{4}\)

\(E=\frac{1:\frac{5}{4}}{\frac{3}{5}}+\frac{1.\frac{7}{4}}{\frac{119}{36}.\frac{36}{17}}+\frac{3}{4}\)

\(E=\frac{4}{5}.\frac{5}{3}+\frac{\frac{7}{4}}{7}+\frac{3}{4}\)

\(E=\frac{4}{3}+\frac{7}{4}.\frac{1}{7}+\frac{3}{4}\)

\(E=\frac{4}{3}+\frac{1}{4}+\frac{3}{4}\)

\(E=\frac{4}{3}+1=\frac{7}{3}\)

Bấm máy tính:

E = \(\frac{4}{3}+\frac{1}{4}+\frac{3}{5}:\frac{4}{5}\)

E = \(\frac{4}{3}+\frac{1}{4}+\frac{3}{4}\)

E = \(\frac{7}{3}\)

Vậy E = \(\frac{7}{3}\)

\(\left(3-\frac{1}{4}+\frac{2}{3}\right)-\left(5+\frac{1}{3}-\frac{6}{5}\right)-\left(6-\frac{7}{4}+\frac{3}{2}\right)\)

\(=3-\frac{1}{4}+\frac{2}{3}-5-\frac{1}{3}+\frac{6}{5}-6+\frac{7}{4}-\frac{3}{2}\)

\(=\left(3-5-6\right)+\left(-\frac{1}{4}+\frac{7}{4}-\frac{3}{2}\right)+\left(\frac{2}{3}-\frac{1}{3}\right)+\frac{6}{5}\)

\(=-8+\frac{1}{3}+\frac{6}{5}\)

\(=-\frac{97}{15}\)

= 3 - 1/4 +2/3 - 5 - 1/3 + 6/5 - 6  + 7/4 - 3/2

= 2/3 . -3/2 . ( 3 + 5 + 6 ) . ( 2/3 + 1/3 ) . ( -1/4 - 7/4) 

= -1 . 14 . 1 . 6/4

= -14 . 1 . 6/4

= -14 . 6/4

= -84/4 = -21

\(\left(3-\frac{1}{4}+\frac{2}{3}\right)-\left(5+\frac{1}{3}-\frac{6}{5}\right)-\left(6-\frac{7}{4}+\frac{3}{2}\right)\)

\(=3+\frac{-1}{4}+\frac{2}{3}-5+\frac{-1}{3}+\frac{6}{5}-6+\frac{7}{4}+\frac{-3}{2}\)

\(=3+\frac{-1}{4}+\frac{2}{3}+-5+\frac{6}{5}+-\frac{1}{3}+-6+\frac{7}{4}+\frac{-3}{2}\)

\(=\left(3+-5+-6\right)+\left(-\frac{1}{4}+\frac{7}{4}\right)+\left(-\frac{1}{3}+\frac{2}{3}\right)+\frac{6}{5}+\frac{-3}{2}\)

\(=-8+\frac{3}{2}+\frac{1}{3}+\frac{6}{5}+\frac{-3}{2}\)

\(=\left(\frac{3}{2}+\frac{-3}{2}\right)+\left(\frac{6}{5}+\frac{1}{3}+-8\right)\)

\(=\frac{18}{15}+\frac{5}{15}+\frac{-120}{15}\)

\(=-\frac{97}{15}\)