a.\(12,5.\left(-\dfrac{5}{7}\right)+1,5.\left(-\dfrac{5}{7}\right)\)

\(=\left(-\dfrac{5}{7}\right).\left(12,5+1,5\right)\)

\(=-10\)

b,\(\left(-\dfrac{2}{5}-\dfrac{3}{7}\right):\dfrac{4}{5}+\left(-\dfrac{1}{5}+\dfrac{3}{7}\right):\dfrac{4}{5}\)

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

\(=-\dfrac{3}{5}:\dfrac{4}{5}\)

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

c,\(12.\left(-\dfrac{2}{3}\right)^2+\dfrac{4}{3}\)

\(=12.\dfrac{4}{9}+\dfrac{4}{3}\)

\(=\dfrac{16}{3}+\dfrac{4}{3}\)

\(=\dfrac{20}{3}\)

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

\(=\dfrac{1}{1}:\dfrac{1}{144}\)

\(=144\)

e,\(15.\left(-\dfrac{2}{3}\right)^2-\dfrac{7}{3}\)

\(=15.\dfrac{4}{9}-\dfrac{7}{3}\)

\(=\dfrac{20}{3}-\dfrac{7}{3}\)

\(=\dfrac{13}{3}\)

a) = ( 12,5 +1,5 ). \(\left(-\dfrac{5}{7}\right)\)

= 14 . \(\left(-\dfrac{5}{7}\right)\)

= -10

b) = (\(-\dfrac{2}{5}+-\dfrac{1}{5}\)) + \(\left(\dfrac{3}{7}-\dfrac{3}{7}\right)\): \(\dfrac{4}{5}\)

= \(\left(-\dfrac{3}{5}+0\right)\): \(\dfrac{4}{5}\)

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

c) = \(\left(12.-\dfrac{2}{9}\right)\) + \(\dfrac{4}{3}\)

= \(\dfrac{8}{3}\) + \(\dfrac{4}{3}\)

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

d) = 1: \(\dfrac{23}{48}\)

=\(\dfrac{48}{23}\)

e) =\(\left(15.-\dfrac{2}{9}\right)-\dfrac{7}{3}\)

= \(\left(-\dfrac{10}{3}\right)-\dfrac{7}{3}\)

=\(-\dfrac{17}{3}\)

f) = 10 485.76

a, \(12,5.\left(\dfrac{-5}{7}\right)+1,5.\left(\dfrac{-5}{7}\right)\)

\(=\left(\dfrac{-5}{7}\right).\left(12,5+1,5\right)=\left(\dfrac{-5}{7}\right).14=-10\)

b, \(\left(\dfrac{-2}{5}-\dfrac{3}{7}\right):\dfrac{4}{5}+\left(\dfrac{-1}{5}+\dfrac{3}{7}\right):\dfrac{4}{5}\)

\(=\left[\left(-\dfrac{2}{5}-\dfrac{1}{5}\right)+\left(\dfrac{-3}{7}+\dfrac{3}{7}\right)\right]:\dfrac{4}{5}\)

\(=\left(\dfrac{-3}{5}+0\right):\dfrac{4}{5}=\dfrac{-3}{5}.\dfrac{5}{4}=\dfrac{-3}{4}\)

c, \(12.\left(\dfrac{-2}{3}\right)^2+\dfrac{4}{3}\)

\(=12.\left(\dfrac{-2^2}{3^2}\right)+\dfrac{4}{3}=12.\left(\dfrac{4}{9}\right)+\dfrac{4}{3}=\dfrac{16}{3}+\dfrac{4}{3}=5\)

d, \(1:\left(\dfrac{2}{3}-\dfrac{3}{4}\right)^2=1:\left(\dfrac{-1}{12}\right)^2=1:\dfrac{1}{144}=144\)

e, \(15.\left(\dfrac{-2}{3}\right)^2-\dfrac{7}{3}\)

\(=15.\dfrac{4}{9}-\dfrac{7}{3}=\dfrac{20}{3}-\dfrac{7}{3}=\dfrac{13}{3}\)

a) \(\left(\dfrac{3}{7}+\dfrac{1}{2}\right)^2=\left(\dfrac{13}{14}\right)^2=\dfrac{169}{196}\)

b) \(\left(\dfrac{3}{4}-\dfrac{5}{6}\right)^2=\left(\dfrac{-1}{12}\right)^2=\dfrac{1}{144}\)

c) \(\dfrac{5^4.20^4}{25^5.4^5}=\dfrac{\left(5.20\right)^4}{\left(25.4\right)^5}=\dfrac{100^4}{100^5}=\dfrac{1}{100}\)

d) \(\left(\dfrac{-10}{3}\right)^5.\left(\dfrac{-6}{5}\right)^4=\dfrac{-10^5}{3^5}.\dfrac{-6^4}{5^4}=\dfrac{-\left(2.5\right)^5.\left(3.2\right)^4}{3^5.5^4}=\dfrac{-29.5}{3}=-853\dfrac{1}{3}\)

Toàn câu dễ nên bạn tự làm đi.

Trong lúc bạn đánh xong bài này thì bạn có thể làm xong rồi đó.

Đừng có ỷ lại vào người khác ,động não lên.

a: \(=\dfrac{5^8\cdot2^8}{5^{10}\cdot2^{10}}=\dfrac{1}{100}\)

b: =7/2+2/7

=49/14+4/14

=53/14

c: \(=\dfrac{11}{12}\cdot\dfrac{16}{33}\cdot\dfrac{3}{5}=\dfrac{1}{3}\cdot\dfrac{3}{5}\cdot\dfrac{4}{3}=\dfrac{1}{5}\cdot\dfrac{4}{3}=\dfrac{4}{15}\)

d: \(=15\cdot\dfrac{4}{9}\cdot\dfrac{-7}{3}=\dfrac{15}{27}\cdot\left(-28\right)=-28\cdot\dfrac{5}{9}=-\dfrac{140}{9}\)

g: \(=\left(\dfrac{21}{47}+\dfrac{26}{47}\right)+\left(\dfrac{9}{45}+\dfrac{36}{45}\right)=1+1=2\)

j: =12*4/9+4/3

=16/3+4/3

=20/3

2: \(=\dfrac{203}{60}\cdot\dfrac{81}{1225}=\dfrac{783}{3500}\)

a) =

b) =

c) =

d) = .

a) \(\left(\dfrac{3}{7}+\dfrac{1}{2}\right)^2=\left(\dfrac{6}{14}+\dfrac{7}{17}\right)^2=\left(\dfrac{13}{12}\right)^2=\dfrac{13^2}{12^2}=\dfrac{169}{144}\)

b)\(\left(\dfrac{3}{4}-\dfrac{5}{6}\right)^2=\left(\dfrac{9}{12}-\dfrac{10}{12}\right)^2=\left(\dfrac{-1}{12}\right)^2=\dfrac{\left(-1\right)^2}{12^2}=\dfrac{1}{144}\)

c)\(\dfrac{5^4.20^4}{25^5.4^5}=\dfrac{5^4.5^4.2^8}{5^{10}.2^{10}}=\dfrac{5^8.2^8}{5^8.5^2.2^8.2^2}=\dfrac{1}{5^2.2^2}=\dfrac{1}{25.4}=\dfrac{1}{100}\)

d)\(\left(\dfrac{-10}{3}\right)^5.\left(\dfrac{-6}{5}\right)^4=\dfrac{\left(-10\right)^5.\left(-6\right)^4}{3^5.5^4}=\dfrac{\left(-2\right)^5.5^5.2^4.3^4}{3^4.3.5^4}=\dfrac{\left(-2\right)^5.5.5^42^4}{3.5^4}=\dfrac{\left(-2\right)^5.5.2^4}{3}=\dfrac{-2560}{3}=-853\dfrac{1}{3}\)

Câu 2: 

\(B=\dfrac{5^{21}\cdot\left(2\cdot5-9\right)}{5^{20}}\cdot\dfrac{7^{15}\left(7+3\right)}{15\cdot7^{15}-95\cdot7^{14}}\)

\(=\dfrac{5\cdot1}{1}\cdot\dfrac{7^{15}\cdot10}{7^{14}\cdot\left(15\cdot7-95\right)}\)

\(=5\cdot\dfrac{7\cdot10}{105-95}=5\cdot7=35\)

a) \(\left(1,25\right)^3.8^3=\left(1,25.8\right)^3=1000\)

b) \(\left(\dfrac{-11}{9}\right)^4.\left(\dfrac{27}{22}\right)^4=\left(\dfrac{-11}{9}.\dfrac{27}{22}\right)^4=\left(\dfrac{-11.9.3}{9.2.\left(-11\right)}\right)^4\)

\(=\left(\dfrac{3}{2}\right)^4=\dfrac{81}{16}\)

c) \(\left(\dfrac{3}{7}+\dfrac{1}{2}\right)^2=\left(\dfrac{13}{14}\right)^2=\dfrac{169}{196}\)

d) \(\dfrac{5^4.20^4}{25^5.4^5}=\dfrac{\left(5.20\right)^4}{\left(25.4\right)^5}=\dfrac{100^4}{100^5}=100^{-1}=0,01\)

Em chuyển hỗn số thành phân số theo CT(\(a\dfrac{b}{c}=\dfrac{a.c+b}{c}\)) tính trong ngoặc trước rồi nhân phân số theo CT: (\(\dfrac{a}{b}.\dfrac{c}{d}=\dfrac{a.c}{b.d}\)) nha.

D= 15.(-1/5/7-2/7)+(-105).1/105= 15.(-2)+(-1)= -30-1= -31

ngu

Giải:

a)(-7/15-27/70)-(8/15+43/70)

=-7/15-27/70-8/15-43/70

=(-7/15-8/15)+(-27/70-43/70)

=-1+(-1)

=-2

b)3/7+(-1/5+-3/7)

=3/7-1/5+-3/7

=(3/7+-3/7)-1/5

=0-1/5

=-1/5

c)(4-12/5).25/8-2/5:-4/25

=8/5.25/8-(-5/2)

=5+5/2

=15/2

d)(-5/24+3/4-7/12):(-5/16)

=-1/24:(-5/16)

=2/15

e)-5/7.2/11+-5/7.9/11

=-5/7.(2/11+9/11)

=-5/7.1

=-5/7

g)6/7+5/4:(-5)-(-1/28).(-2)²

=6/7+(-1/4)-(-1/28).4

=6/7+(-1/4)-(-1/7)

=6/7-1/4+1/7

=(6/7+1/7)-1/4

=1-1/4

=3/4

Chúc bạn học tốt!