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20 tháng 6 2020

\(a,\frac{-2}{5}:\left(\frac{-3}{5}+\frac{3}{2}\right)\)

\(=\frac{-2}{5}:\left(-\frac{6}{10}+\frac{15}{10}\right)=\frac{-2}{5}:\frac{9}{10}\)

\(=\frac{-2}{5}.\frac{10}{9}=\frac{-20}{45}=-\frac{4}{9}\)

\(b,\frac{-5}{2016}.\frac{2}{11}+\frac{-5}{2016}.\frac{9}{11}+1\frac{5}{2016}\)

\(=\frac{-5}{2016}.\left(\frac{2}{11}+\frac{9}{11}\right)+1\frac{5}{2016}\)

\(=-\frac{5}{2016}+1+\frac{5}{2016}=1\)

5 tháng 4 2017

C\(\frac{1}{1}-\frac{1}{2.3}+\frac{1}{3.4}-\frac{1}{4.5}+\frac{1}{5.6}\)-\(\frac{1}{6.7}\)+\(\frac{1}{7.8}\)-\(\frac{1}{8.9}+\frac{1}{9.10}\)

c=\(\frac{1}{1}-\frac{1}{10}\)

c=\(\frac{9}{10}\)

còn a và b rễ lắm mình ko thích làm bài rễ đâu bạn cố chờ lời giải khác nhé!

8 tháng 6 2019

Bài 1:

\(a,22\frac{1}{2}.\frac{7}{9}+50\%-1,25\)

=\(\frac{45}{2}.\frac{7}{9}+\frac{1}{2}-\frac{5}{4}\)

=\(\frac{35}{2}+\frac{1}{2}-\frac{5}{4}\)

=\(\frac{70}{4}+\frac{2}{4}-\frac{5}{4}\)

=\(\frac{67}{4}\)

\(b,1,4.\frac{15}{49}-\left(\frac{4}{5}+\frac{2}{3}\right):2\frac{1}{5}\)

=\(\frac{7}{5}.\frac{15}{49}-\left(\frac{12}{15}+\frac{10}{15}\right):\frac{11}{5}\)

=\(\frac{3}{7}-\frac{22}{15}.\frac{5}{11}\)

=\(\frac{3}{7}-\frac{2}{3}\)

=\(-\frac{5}{21}\)

\(c,125\%.\left(-\frac{1}{2}\right)^2:\left(1\frac{5}{6}-1,6\right)+2016^0\)

=\(\frac{5}{4}.\frac{1}{4}:\left(\frac{11}{6}-\frac{8}{5}\right)+1\)

=\(\frac{5}{16}:\frac{7}{30}+1\)

=\(\frac{131}{56}\)

\(d,1,4.\frac{15}{49}-\left(20\%+\frac{2}{3}\right):2\frac{1}{5}\)

=\(\frac{7}{5}.\frac{15}{49}-\left(\frac{1}{5}+\frac{2}{3}\right):\frac{11}{5}\)

=\(\frac{3}{7}-\frac{13}{15}:\frac{11}{5}\)

=\(\frac{3}{7}-\frac{13}{33}\)

=\(\frac{8}{231}\)

Bài đ làm giống hệt như bài c

Bài 2 :

\(a,\left|\frac{3}{4}.x-\frac{1}{2}\right|=\frac{1}{4}\)

=>\(\left[{}\begin{matrix}\frac{3}{4}.x-\frac{1}{2}=\frac{1}{4}\\\frac{3}{4}.x-\frac{1}{2}=-\frac{1}{4}\end{matrix}\right.\)

=>\(\left[{}\begin{matrix}\frac{3}{4}.x=\frac{1}{4}+\frac{1}{2}=\frac{3}{4}\\\frac{3}{4}.x=-\frac{1}{4}+\frac{1}{2}=\frac{1}{4}\end{matrix}\right.\)

=>\(\left[{}\begin{matrix}x=\frac{3}{4}:\frac{3}{4}=1\\x=\frac{1}{4}:\frac{3}{4}=\frac{1}{3}\end{matrix}\right.\)

Vậy x ∈{1;\(\frac{1}{3}\)}

\(b,\frac{5}{3}.x-\frac{2}{5}.x=\frac{19}{10}\)

=>\(\frac{19}{15}.x=\frac{19}{10}\)

=>\(x=\frac{19}{10}:\frac{19}{15}=\frac{3}{2}\)

Vậy x ∈ {\(\frac{3}{2}\)}

c,\(\left|2.x-\frac{1}{3}\right|=\frac{2}{9}\)

=>\(\left[{}\begin{matrix}2.x-\frac{1}{3}=\frac{2}{9}\\2.x-\frac{1}{3}=-\frac{2}{9}\end{matrix}\right.\)

=>\(\left[{}\begin{matrix}2.x=\frac{2}{9}+\frac{1}{3}=\frac{5}{9}\\2.x=-\frac{2}{9}+\frac{1}{3}=\frac{1}{9}\end{matrix}\right.\)

=>\(\left[{}\begin{matrix}x=\frac{5}{9}:2=\frac{5}{18}\\x=\frac{1}{9}:2=\frac{1}{18}\end{matrix}\right.\)

Vậy x∈{\(\frac{5}{18};\frac{1}{18}\)}

\(d,x-30\%.x=-1\frac{1}{5}\)

=\(70\%x=-\frac{6}{5}\)

=\(\frac{7}{10}.x=-\frac{6}{5}\)

=>\(x=-\frac{6}{5}:\frac{7}{10}=-\frac{12}{7}\)

Vậy x∈{\(-\frac{12}{7}\)}

8 tháng 6 2019

Bài 2

a/

\(\Rightarrow\left[{}\begin{matrix}\frac{3}{4}.x-\frac{1}{2}=\frac{1}{4}\\\frac{3}{4}.x-\frac{1}{2}=-\frac{1}{4}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}\frac{3}{4}.x=\frac{1}{4}+\frac{1}{2}\\\frac{3}{4}.x=-\frac{1}{4}+\frac{1}{2}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}\frac{3}{4}.x=\frac{3}{4}\\\frac{3}{4}.x=\frac{1}{4}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=\frac{3}{4}:\frac{3}{4}\\x=\frac{1}{4}:\frac{3}{4}\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=1\\x=\frac{1}{3}\end{matrix}\right.\)

Vậy \(x=1\) hoặc \(x=\frac{1}{3}\)

b/ Đặt x làm thừa số chung rồi tính như bình thường

c/ Tương tự câu a

d/ Tương tự câu b

17 tháng 4 2018

a) -1 - 2 + 3 + 4 - 5 - 6 + 7 + 8 - 9 - 10 + 11 + 12 - ... - 2013 - 2014 + 2015 + 2016

= ( -1 - 2 + 3 + 4 ) - ( 5 + 6 - 7 - 8 ) - ( 9 + 10 - 11 - 12 ) - .......... - ( 2013 + 2014 - 2015 - 2016 )

= 4 - ( -4 ) - ( -4 ) - ......... - ( -4 )

= 4 + 4 + 4 +....... + 4

= { [ ( 2016 - 1 ) : 1 + 1 ] : 4 } . 4

= { [ 2015 : 1 + 1 ] : 4 } . 4

= {  2016 : 4 } . 4

= 504 . 4

=  2016

b) \(\left(\frac{1}{2}-1\right):\left(\frac{1}{3}-1\right):\left(\frac{1}{4}-1\right):\left(\frac{1}{5}-1\right):.........:\left(\frac{1}{100}-1\right)\)

\(=\frac{-1}{2}:\frac{-2}{3}:\frac{-3}{4}:\frac{-4}{5}:......:\frac{-99}{100}\)

\(=\frac{-1}{2}.\frac{3}{-2}.\frac{4}{-3}.\frac{5}{-4}.......\frac{100}{-99}\)

\(=\frac{-1.3.4........100}{2.2.3.4......99}\)

\(=\frac{-1.100}{2.2}\)

\(=\frac{-100}{4}\)

\(=-25\)

17 tháng 4 2018

a)    -1-2+3+4-5-6+7+8+...+2016=-3+3-7+7-...-2016+2016=0

b)     \(\left(\frac{1}{2}-1\right):...:\left(\frac{1}{100}-1\right)=\frac{-1}{2}:\frac{-2}{3}:\frac{-3}{4}:...:\frac{-99}{100}\)

\(=\)\(\frac{-1}{2}.\frac{-3}{2}.....\frac{-100}{99}=\frac{-1}{2}.\left(-50\right)=25\)

2 tháng 7 2019

a)\(\frac{11^4.6-11^5}{11^4-11^5}:\frac{9^8.3-9^9}{9^8.5+9^8.7}\)

\(=1.6:\frac{9^8.3-9^8.9}{9^8.\left(5+7\right)}\)

\(=6:\frac{9^8.\left(3-9\right)}{9^8.12}\)

\(=6:\frac{9^8.\left(-6\right)}{9^8.12}\)

\(=6:\left(-\frac{6}{12}\right)\)

\(=6:\left(-\frac{1}{2}\right)\)

\(=-12\)

b) 3/5 : ( -1/5-1/6)+3/5:(-1/3-16/15) ( mình chuyển về ps luôn )

=3/5: (-11/30) + 3/5 : (-7/5) 

=3/5:[-11/30+(-7/5)]

=3/5:53/30

=18/53

c) (1/2-13/14):5/7-(-2/21+1/7):5/7

= -3/7:5/7-1/21:5/7

=(-3/7-1/21):5/7

=-10/21:5/7

=-2/3

câu b vá c mình làm tắt nha. chúc bạn học tốt