\(\left(\frac{136}{15}-\frac{28}{5}+\frac{62}{10}\right).\frac{21}{24}\)

\(=\left(\frac{136}{15}-\frac{28}{5}+\frac{31}{5}\right).\frac{21}{24}\)

\(=\left[\frac{136}{15}-\left(\frac{28}{5}-\frac{31}{5}\right)\right].\frac{21}{24}\)

\(=\left(\frac{136}{15}+\frac{3}{5}\right).\frac{21}{24}\)

\(=\frac{29}{3}.\frac{21}{24}\)

\(=\frac{203}{24}\)

Study well ! >_<

\(\frac{203}{24}\)

b)B=(136/15 - 28/5 +31/5)^.21/24

    B=(136/15-(28/5 - 31/5)^.21/24

     B=(136/15 + 3/5)^.21/24

      B=29/3^.21/24

      B=203/24

\(A=1.2.3...100-1.2.3...99-1.2.3...98.99^2\)

\(=1.2.3...99\left(100-1-99\right)\)

\(=1.2.3...99.0=0\)

= 203/24

\(\left(\frac{136}{15}-\frac{28}{5}+\frac{62}{10}\right)\cdot\frac{21}{24}\)

=

\(=\left(\frac{272}{30}+-\frac{168}{30}+\frac{186}{30}\right).\frac{7}{8}\)\(=\frac{29}{3}.\frac{7}{8}=\frac{203}{24}\)

a) A= ( 136/15 - 28/5 + 62/10) .21/24

A= (136/15 - 84/15 + 93/15) . 7/8

A= 145/15. 7/8

A= 203/24

b) B= 70 .( 131313.565656 + 131313/727272 + 131313/ 909090)

= 70. ( 13/56+ 13/72 + 13/90)

= 70 . 39/70

= 39

1)

a)

\(\frac{-5}{6}.\frac{120}{25}< x< \frac{-7}{15}.\frac{9}{14}\)

\(\frac{-1}{1}.\frac{20}{5}< x< \frac{-1}{5}.\frac{3}{2}\)

\(\frac{-20}{5}< x< \frac{-3}{10}\)

\(\frac{-40}{10}< x< \frac{-3}{10}\)

\(\Rightarrow Z\in\left\{-4;-5;-6;-7;-8;-9;-10;...;-39\right\}\)

\(\left(\frac{-5}{3}\right)^3< x< \frac{-24}{35}.\frac{-5}{6}\)

\(\frac{25}{3}< x< \frac{-4}{7}.\frac{1}{1}\)

\(\frac{-25}{3}< x< \frac{-4}{7}\)

\(\frac{-175}{21}< x< \frac{-12}{21}\)

\(\Rightarrow Z\in\left\{-13;-14;-15;-16;...;-174\right\}\)

2)

a)

\(\left(\frac{9}{10}-\frac{15}{16}\right).\left(\frac{5}{12}-\frac{11}{15}-\frac{7}{20}\right)\)

\(=\left(\frac{72}{80}-\frac{75}{80}\right).\left(\frac{25}{60}-\frac{44}{60}-\frac{21}{60}\right)\)

\(=\frac{-3}{80}.\frac{-40}{60}\)

\(=\frac{-1}{-2}.\frac{-1}{-20}\)

\(=\frac{1}{40}\)

A) \(\frac{7}{\left(x+3\right)\left(x+10\right)}+\frac{11}{\left(x+10\right)\left(x+21\right)}+\frac{13}{\left(x+21\right)\left(x+34\right)}\)

\(=\frac{\left(x+10\right)-\left(x+3\right)}{\left(x+3\right)\left(x+10\right)}+\frac{\left(x+21\right)-\left(x+10\right)}{\left(x+10\right)\left(x+21\right)}+\frac{\left(x+34\right)-\left(x+21\right)}{\left(x+21\right)\left(x+34\right)}\)

\(=\frac{1}{x+3}-\frac{1}{x+10}+\frac{1}{x+10}-\frac{1}{x+21}+\frac{1}{x+21}-\frac{1}{x+34}\)

\(=\frac{1}{x+3}-\frac{1}{x+34}\)

\(=\frac{\left(x+34\right)-\left(x+3\right)}{\left(x+3\right)\left(x+34\right)}\)\(=\frac{x}{\left(x+3\right)\left(x+34\right)}\)

\(\Rightarrow\left(x+34\right)-\left(x+3\right)=x\)

\(\Rightarrow x=31\)

Vậy, x = 31 

Bạn áp dụng: \(\frac{k}{x\cdot\left(x+k\right)}=\frac{1}{x}-\frac{1}{x+k}\) với    \(x,k\inℝ;x\ne0;x\ne-k\)

Chứng minh: \(\frac{1}{x}-\frac{1}{x+k}=\frac{x+k}{x\left(x+k\right)}-\frac{x}{x\left(x+k\right)}=\frac{x+k-x}{x\left(x+k\right)}=\frac{k}{x\left(x+k\right)}\)

B) \(\frac{\left(x-4\right)-\left(x-7\right)}{\left(x-7\right)\left(x-4\right)}+\frac{\left(x-7\right)-\left(x-13\right)}{\left(x-13\right)\left(x-7\right)}+\frac{\left(x-13\right)-\left(x-28\right)}{\left(x-28\right)\left(x-13\right)}\)

\(=\frac{1}{x-7}-\frac{1}{x-4}+\frac{1}{x-13}-\frac{1}{x-7}+\frac{1}{x-28}-\frac{1}{x-13}\)

\(=\frac{1}{x-28}-\frac{1}{x-4}=-\frac{5}{2}+\frac{1}{x-28}\)

\(\Leftrightarrow\frac{1}{x-28}-\frac{1}{x-4}-\frac{1}{x-28}=-\frac{5}{2}\)

\(\Leftrightarrow\frac{1}{x-4}=\frac{5}{2}\)

=> 5x - 20 = 2

=> 5x = 22 

\(\Rightarrow x=\frac{22}{5}=4,4\)

Vậy, x = 4,4

yutyugubhujyikiu

a) \(\frac{-28}{19}\). \(\frac{\left(-38\right)}{14}\)= 4

b) \(\frac{-21}{16}\). \(\frac{\left(-24\right)}{7}\)= \(\frac{9}{2}\)

c) \(\frac{12}{17}\). \(\frac{\left(-34\right)}{9}\)= \(\frac{-8}{3}\)

d) \(\frac{\left(-15\right)}{4}\): \(\frac{21}{10}\)= \(\frac{-25}{14}\)

e) \(-2\frac{1}{7}\): \(-1\frac{1}{14}\)= 2

nhớ ủng hộ mik nha mn

a.=4

b.=119/24

c.= -8/3

d.= -25/14

Mình chỉ làm đc từng này thôi

\(a,\frac{-28}{19}.\frac{\left(-38\right)}{14}\)

\(=\frac{-28.\left(-38\right)}{19.14}\)

\(=\frac{-2.\left(-2\right)}{1.1}\)

\(=-2.\left(-2\right)=4\)

\(b,\frac{-21}{16}.\frac{\left(-24\right)}{7}\)

\(=\frac{-21.\left(-24\right)}{16.7}\)

\(=\frac{-3.\left(-3\right)}{2.1}\)

\(=\frac{9}{2}\)

\(c,\frac{12}{17}.\frac{\left(-34\right)}{9}\)

\(=\frac{12.\left(-34\right)}{17.9}\)

\(=\frac{4.\left(-2\right)}{1.3}\)

\(=\frac{-8}{3}\)

\(d,\frac{\left(-15\right)}{4}:\frac{21}{10}\)

\(=\frac{\left(-15\right)}{4}.\frac{10}{21}\)

\(=\frac{\left(-5\right).5}{2.7}\)

\(=\frac{-25}{14}\)

\(e,-2\frac{1}{7}:\left(-1\frac{1}{14}\right)\)

\(=\frac{-15}{7}:\frac{-15}{14}\)

\(=\frac{-15}{7}.\frac{14}{-15}\)

\(=\frac{1.2}{1.1}\)

\(=2\)

                                 Cảm ơn mình bằng 1 dấu tích đúng nha \(!!!\)