a: \(=\dfrac{5}{4}\cdot\dfrac{2}{5}\cdot\dfrac{17}{21}\cdot\dfrac{7}{34}=\dfrac{1}{2}\cdot\dfrac{1}{2}\cdot\dfrac{1}{3}=\dfrac{1}{12}\)

b: =>0,5^x(0,5+1)=1,5

=>0,5^x=1

=>x=0

c: =>x*0,05-0,25*x=-1,2

=>-0,3*x=-1,2

=>x=4

d: =>x-1=1 hoặc x-1=-1

=>x=0 hoặc x=2

e: =5+4=9

 \(\frac{13}{25}+\frac{6}{41}-\frac{38}{25}+\frac{35}{41}-\frac{1}{2}\) 

\(=\left(\frac{13}{25}-\frac{38}{25}\right)+\left(\frac{6}{41}+\frac{35}{41}\right)-\frac{1}{2}\) 

\(=-1+1-\frac{1}{2}=0-\frac{1}{2}\) 

\(=\frac{-1}{2}\) 

\(1\frac{4}{23}+\frac{5}{21}-\frac{4}{23}+0,5+\frac{16}{21}\) 

\(=\left(1\frac{4}{23}-\frac{4}{23}\right)+\left(\frac{5}{21}+\frac{16}{21}\right)+0,5\) 

\(=1+1+0,5=2,5\)

\(\frac{13}{25}+\frac{4}{41}-\frac{38}{25}+\frac{35}{41}-\frac{1}{2}\)

= \(\left(\frac{13}{25}-\frac{38}{25}\right)+\left(\frac{6}{41}+\frac{35}{41}\right)-\frac{1}{2}\)

= \(-1+1-\frac{1}{2}=-\frac{1}{2}\)

\(1\frac{4}{23}+\frac{5}{21}-\frac{4}{23}+0,5+\frac{16}{21}\)

=\(\left(1\frac{4}{23}-\frac{4}{23}\right)+\left(\frac{5}{21}+\frac{16}{21}\right)+0,5\)

= \(1+1+0,5=2,5\)

\(=\dfrac{29}{25}+1-\dfrac{1}{2}=\dfrac{29}{25}+\dfrac{1}{2}=\dfrac{83}{50}\)

`#3107.101107`

a)

`2/5 \sqrt{25} - 1/2 \sqrt{4}`

`= 2/5 * \sqrt{5^2} - 1/2 * \sqrt{2^2}`

`= 2/5*5 - 1/2*2`

`= 2 - 1`

`= 1`

b)

`0,5*\sqrt{0,09} + 5*\sqrt{0,81}`

`= 0,5*\sqrt{(0,3)^2} + 5*\sqrt{(0,9)^2}`

`= 0,5*0,3 + 5*0,9`

`= 0,15 + 4,5`

`= 4,65`

c)

`2/5\sqrt{25/36} - 5/2\sqrt{4/25}`

`= 2/5*\sqrt{(5^2)/(6^2)} - 5/2*\sqrt{(2^2)/(5^2)}`

`= 2/5*5/6 - 5/2*2/5`

`= 1/3 - 1`

`= -2/3`

d)

`-2 \sqrt{(-36)/(-16)} + 5 \sqrt{(-81)/(-25)}`

`= -2*\sqrt{36/16} + 5*\sqrt{81/25}`

`= -2*\sqrt{(6^2)/(4^2)} + 5*\sqrt{(9^2)/(5^2)}`

`= -2*6/4 + 5*9/5`

`= -3 + 9`

`= 6`

Xem lại kết quả câu c nhé bạn!

a) \(1\frac{4}{23}+\frac{5}{21}-\frac{4}{23}+0,5+\frac{16}{21}\)

\(=\left(1\frac{4}{23}-\frac{4}{23}\right)+\left(\frac{5}{21}+\frac{16}{21}\right)+0,5\)

\(=1+1+0,5\)

\(=2+0,5\)

\(=2,5.\)

b) \(\sqrt{\frac{25}{81}}:2\frac{2}{5}-4\frac{5}{9}:2\frac{2}{5}\)

\(=\frac{5}{9}:\frac{12}{5}-\frac{41}{9}:\frac{12}{5}\)

\(=\left(\frac{5}{9}-\frac{41}{9}\right):\frac{12}{5}\)

\(=\left(-4\right):\frac{12}{5}\)

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

c) \(6.\left(-\frac{-1}{2}\right)^2+\frac{3}{5}\)

\(=6.\left(\frac{1}{2}\right)^2+\frac{3}{5}\)

\(=6.\frac{1}{4}+\frac{3}{5}\)

\(=\frac{3}{2}+\frac{3}{5}\)

\(=\frac{21}{10}.\)

Chúc bạn học tốt!

a: \(\left(\frac{9}{25}-2,18\right):\left(3\frac45+0,2\right)\)

=(0,36-2,18):(3,8+0,2)

=-1,82:4

=-0,455

b: \(\frac38\cdot19\frac13-\frac38\cdot33\frac13\)

\(=\frac38\cdot\left(19+\frac13-33-\frac13\right)\)

\(=\frac38\cdot\left(-14\right)=-\frac{42}{8}=-\frac{21}{4}\)

c: \(1\frac{4}{23}+\frac{5}{21}-\frac{4}{23}+0,5+\frac{16}{21}\)

\(=\left(1+\frac{4}{23}-\frac{4}{23}\right)+\left(\frac{5}{21}+\frac{16}{21}\right)+0,5\)

=1+1+0,5

=2,5

d: Sửa đề: \(\frac{2^{12}\cdot3^5-4^6\cdot81}{2^{12}\cdot3^6+8^4\cdot3^5}\)

\(=\frac{2^{12}\cdot3^5-2^{12}\cdot3^4}{2^{12}\cdot3^6+2^{12}\cdot3^5}=\frac{2^{12}\cdot3^4\cdot\left(3-1\right)}{2^{12}\cdot3^5\cdot\left(3+1\right)}=\frac13\cdot\frac24=\frac13\cdot\frac12=\frac16\)

e: \(4\cdot\left(-\frac12\right)^2-2\cdot\left(-\frac12\right)^2+3\cdot\left(-\frac12\right)+1\)

\(=2\cdot\frac14-\frac32+1\)

=1/2-3/2+1

=-2/2+1

=-1+1

=0

g: \(\sqrt{\frac{4}{81}}:\sqrt{\frac{25}{81}}-1\frac25\)

\(=\frac29:\frac59-\frac75=\frac25-\frac75\)

=-5/5

=-1

`21/25-5/21-[-4]/25-16/21+1/2`

`=(21/25-[-4]/25)-(5/21+16/21)+1/2`

`=25/25-21/21+1/2`

`=1-1+1/2=1/2`

a: \(\dfrac{16}{15}\cdot\dfrac{-5}{14}\cdot\dfrac{54}{24}\cdot\dfrac{56}{21}\)

\(=\dfrac{16}{24}\cdot\dfrac{-5}{15}\cdot\dfrac{54}{21}\cdot\dfrac{56}{14}\)

\(=\dfrac{2}{3}\cdot\dfrac{-1}{3}\cdot\dfrac{18}{7}\cdot4\)

\(=\dfrac{-2\cdot2\cdot4}{7}=-\dfrac{16}{7}\)

b: \(\dfrac{7}{3}\cdot\dfrac{-5}{2}\cdot\dfrac{15}{21}\cdot\dfrac{4}{-5}\)

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

\(=\dfrac{5}{3}\cdot\dfrac{4}{2}=\dfrac{5}{3}\cdot2=\dfrac{10}{3}\)

c: \(\left(-\dfrac{2}{5}+\dfrac{1}{3}\right)\left(\dfrac{3}{2}-\dfrac{3}{7}\right)\)

\(=\dfrac{-2\cdot5+3}{15}\cdot\dfrac{3\cdot7-3\cdot2}{14}\)

\(=\dfrac{-7}{15}\cdot\dfrac{15}{14}=\dfrac{-7}{14}=-\dfrac{1}{2}\)

d: \(\left(\dfrac{1}{2}-\dfrac{1}{3}\right)\left(5-\dfrac{1}{4}\right)\)

\(=\dfrac{3-2}{6}\cdot\dfrac{20-1}{4}\)

\(=\dfrac{1}{6}\cdot\dfrac{19}{4}=\dfrac{19}{24}\)

e: \(\left(\dfrac{4}{5}\right)^2=\dfrac{4^2}{5^2}=\dfrac{16}{25}\)

a: \(=\dfrac{5}{6}\cdot\dfrac{-12}{7}=\dfrac{-10}{7}\)

b: \(=\dfrac{7}{8}\cdot\dfrac{8}{14}=\dfrac{7}{14}=\dfrac{1}{2}\)

c: \(=\dfrac{4}{5}\cdot\dfrac{-15}{8}=\dfrac{-3}{2}\)

d: \(=\dfrac{15}{16}\cdot\dfrac{8}{25}=\dfrac{15}{25}\cdot\dfrac{1}{2}=\dfrac{3}{5}\cdot\dfrac{1}{2}=\dfrac{3}{10}\)

đ: \(=\dfrac{2}{3}-\dfrac{70}{175}=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{10-6}{15}=\dfrac{4}{15}\)