bài 1 tínha)\(-\frac{1}{4}\) b)\(\left(-2\frac{1}{3}\right)^2\) c)(0,5)3 d)\(\left(-1\frac{1}{3}\right)^4\)bai 2 tìm x , biếta)x:\(\left(-\frac{1}{3}\right)^3\)=\(-\frac{1}{3}\) b)\(\left(x \...

KK

Kaito kid

26 tháng 6 2018 - olm

bài 1 tínha)\(-\frac{1}{4}\) b)\(\left(-2\frac{1}{3}\right)^2\) c)(0,5)3 d)\(\left(-1\frac{1}{3}\right)^4\)bai 2 tìm x , biếta)x:\(\left(-\frac{1}{3}\right)^3\)=\(-\frac{1}{3}\) b)\(\left(x+\frac{1}{2}\right)^2=\frac{1}{16}\) c)\(\left(\frac{4}{5}\right):x=\left(\frac{4}{5}\right)^7\) d)\(3x+1=27\)bài 3 so...

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#Toán lớp 7

2

ID

I don't need you

26 tháng 6 2018

Bài 1 và Bài 2 dễ, bn có thể tự làm được!

Bài 3:

a) ta có: 10²⁰ = (10²)¹⁰ = 100¹⁰

=> 100¹⁰>9¹⁰

=> 10²⁰>9¹⁰

b) ta có: (-5)³⁰ = 5³⁰ =( 5³)¹⁰ = 125¹⁰ ( vì là lũy thừa bậc chẵn)

(-3)⁵⁰ = 3⁵⁰ = (3⁵)¹⁰= 243¹⁰

=> 125¹⁰ < 243¹⁰

=> (-5)³⁰ < (-3)⁵⁰

c) ta có: 64⁸ = (2⁶)⁸= 2⁴⁸

16¹² = ( 2⁴)¹² = 2⁴⁸

=> 64⁸ = 16¹²

d) ta có: \(\left(\frac{1}{16}\right)^{10}=\left(\frac{1}{2^4}\right)^{10}=\frac{1}{2^{40}}\)

\(\left(\frac{1}{2}\right)^{50}=\frac{1}{2^{50}}\)

\(\Rightarrow\frac{1}{2^{40}}>\frac{1}{2^{50}}\)

\(\Rightarrow\left(\frac{1}{16}\right)^{10}>\left(\frac{1}{2}\right)^{50}\)

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AH

Anh Huỳnh

26 tháng 6 2018

3.a) Ta có: 9¹⁰=(3²)¹⁰=3²⁰

Mà 10²⁰<3²⁰

Nên 10²⁰<9¹⁰

c)Ta có:64⁸ =(8²)⁸=8¹⁶

16¹²=(2³)¹²=8³⁶

vì 8¹⁶<8³⁶

Nên 64⁸<16²

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QT

Quoc Tran Anh Le

Giáo viên

16 tháng 9 2023

Tính

a) \(\left( {\frac{4}{5} - 1} \right):\frac{3}{5} - \frac{2}{3}.0,5\)

b) \(1 - {\left( {\frac{5}{9} - \frac{2}{3}} \right)^2}:\frac{4}{{27}}\)

c)\(\left[ {\left( {\frac{3}{8} - \frac{5}{{12}}} \right).6 + \frac{1}{3}} \right].4\)

d) \(0,8:\left\{ {0,2 - 7.\left[ {\frac{1}{6} + \left( {\frac{5}{{21}} - \frac{5}{{14}}} \right)} \right]} \right\}\)

#Toán lớp 7

1

HQ

Hà Quang Minh

Giáo viên

16 tháng 9 2023

a)

\(\begin{array}{l}\frac{1}{9} - 0,3.\frac{5}{9} + \frac{1}{3}\\ = \frac{1}{9} - \frac{3}{{10}}.\frac{5}{9} + \frac{1}{3}\\ = \frac{1}{9} - \frac{3}{{2.5}}.\frac{5}{{3.3}} + \frac{1}{3}\\ = \frac{1}{9} - \frac{1}{6} + \frac{1}{3}\\ = \frac{2}{{18}} - \frac{3}{{18}} + \frac{6}{{18}}\\ = \frac{5}{{18}}\end{array}\)

b)

\(\begin{array}{l}{\left( {\frac{{ - 2}}{3}} \right)^2} + \frac{1}{6} - {\left( { - 0,5} \right)^3}\\ = \frac{4}{9} + \frac{1}{6} - \left( {\frac{{ - 1}}{2}} \right)^3\\ = \frac{4}{9} + \frac{1}{6} - \left( {\frac{{ - 1}}{8}} \right)\\ = \frac{4}{9} + \frac{1}{6} + \frac{1}{8}\\ = \frac{{32}}{{72}} + \frac{{12}}{{72}} + \frac{9}{{72}}\\ = \frac{{53}}{{72}}\end{array}\)

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QT

Quoc Tran Anh Le

Giáo viên

19 tháng 9 2023

Tìm x, biết:

a)\(\frac{2}{9}:x + \frac{5}{6} = 0,5;\)

b)\(\frac{3}{4} - \left( {x - \frac{2}{3}} \right) = 1\frac{1}{3};\)

c)\(1\frac{1}{4}:\left( {x - \frac{2}{3}} \right) = 0,75;\)

d)\(\left( { - \frac{5}{6}x + \frac{5}{4}} \right):\frac{3}{2} = \frac{4}{3}\).

#Toán lớp 7

1

HQ

Hà Quang Minh

Giáo viên

19 tháng 9 2023

a)

\(\begin{array}{l}\frac{2}{9}:x + \frac{5}{6} = 0,5\\\frac{2}{9}:x = \frac{1}{2} - \frac{5}{6}\\\frac{2}{9}:x = \frac{3}{6} - \frac{5}{6}\\\frac{2}{9}:x = \frac{{ - 2}}{6}\\x = \frac{2}{9}:\frac{{ - 2}}{6}\\x = \frac{2}{9}.\frac{{ - 6}}{2}\\x = \frac{{ - 2}}{3}\end{array}\)

Vậy \(x = \frac{{ - 2}}{3}\).

b)

\(\begin{array}{l}\frac{3}{4} - \left( {x - \frac{2}{3}} \right) = 1\frac{1}{3}\\x - \frac{2}{3} = \frac{3}{4} - 1\frac{1}{3}\\x - \frac{2}{3} = \frac{3}{4} - \frac{4}{3}\\x - \frac{2}{3} = \frac{9}{{12}} - \frac{{16}}{{12}}\\x - \frac{2}{3} = \frac{{ - 7}}{{12}}\\x = \frac{{ - 7}}{{12}} + \frac{2}{3}\\x = \frac{{ - 7}}{{12}} + \frac{8}{{12}}\\x = \frac{1}{12}\end{array}\)

Vậy\(x = \frac{1}{12}\).

c)

\(\begin{array}{l}1\frac{1}{4}:\left( {x - \frac{2}{3}} \right) = 0,75\\\frac{5}{4}:\left( {x - \frac{2}{3}} \right) = \frac{3}{4}\\x - \frac{2}{3} = \frac{5}{4}:\frac{3}{4}\\x - \frac{2}{3} = \frac{5}{4}.\frac{4}{3}\\x - \frac{2}{3} = \frac{5}{3}\\x = \frac{5}{3} + \frac{2}{3}\\x = \frac{7}{3}\end{array}\)

Vậy \(x = \frac{7}{3}\).

d)

\(\begin{array}{l}\left( { - \frac{5}{6}x + \frac{5}{4}} \right):\frac{3}{2} = \frac{4}{3}\\ - \frac{5}{6}x + \frac{5}{4} = \frac{4}{3}.\frac{3}{2}\\ - \frac{5}{6}x + \frac{5}{4} = 2\\ - \frac{5}{6}x = 2 - \frac{5}{4}\\ - \frac{5}{6}x = \frac{8}{4} - \frac{5}{4}\\ - \frac{5}{6}x = \frac{3}{4}\\x = \frac{3}{4}:\left( { - \frac{5}{6}} \right)\\x = \frac{3}{4}.\frac{{ - 6}}{5}\\x = \frac{{ - 9}}{{10}}\end{array}\)

Vậy \(x = \frac{{ - 9}}{{10}}\).

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BK

Bùi Khánh Linh

16 tháng 8 2019 - olm

Bài 1 : Tìm x biết :a, \(\left|\frac{3}{2}x+\frac{1}{2}\right|=\left|4x-1\right|\)b, \(\left|\frac{5}{4}x-\frac{7}{2}\right|-\left|\frac{5}{8}x+\frac{3}{5}\right|=0\)c,\(\left|\frac{7}{5}x+\frac{2}{3}\right|=\left|\frac{4}{3}x-\frac{1}{4}\right|\)Bài 2 : Tìm x biết :a, | 2x - 5 | = x +1 b, | 3x - 2 | -1 = x c, | 3x - 7 | = 2x + 1d, | 2x-1 | +1 =...

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#Toán lớp 7

3

EC

Edogawa Conan

16 tháng 8 2019

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

=> \(\orbr{\begin{cases}\frac{3}{2}x+\frac{1}{2}=4x-1\\\frac{3}{2}x+\frac{1}{2}=1-4x\end{cases}}\)

=> \(\orbr{\begin{cases}-\frac{5}{2}x=-\frac{3}{2}\\\frac{11}{2}x=\frac{1}{2}\end{cases}}\)

=> \(\orbr{\begin{cases}x=\frac{5}{3}\\x=\frac{1}{11}\end{cases}}\)

b) \(\left|\frac{5}{4}x-\frac{7}{2}\right|-\left|\frac{5}{8}x+\frac{3}{5}\right|=0\)

=>\(\left|\frac{5}{4}x-\frac{7}{2}\right|=\left|\frac{5}{8}x+\frac{3}{5}\right|\)

=> \(\orbr{\begin{cases}\frac{5}{4}x-\frac{7}{2}=\frac{5}{8}x+\frac{3}{5}\\\frac{5}{4}x-\frac{7}{2}=-\frac{5}{8}x-\frac{3}{5}\end{cases}}\)

=> \(\orbr{\begin{cases}\frac{5}{8}x=\frac{41}{10}\\\frac{15}{8}x=\frac{29}{10}\end{cases}}\)

=> \(\orbr{\begin{cases}x=\frac{164}{25}\\x=\frac{116}{75}\end{cases}}\)

c) TT

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HQ

Huỳnh Quang Sang

16 tháng 8 2019

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

=> \(\orbr{\begin{cases}\frac{3}{2}x+\frac{1}{2}=4x-1\\-\frac{3}{2}x-\frac{1}{2}=4x-1\end{cases}}\)

=> \(\orbr{\begin{cases}\frac{3}{2}x+\frac{1}{2}-4x=-1\\-\frac{3}{2}x-\frac{1}{2}-4x=-1\end{cases}}\)

=> \(\orbr{\begin{cases}x=\frac{3}{5}\\x=\frac{1}{11}\end{cases}}\)

\(b,\left|\frac{5}{4}x-\frac{7}{2}\right|-\left|\frac{5}{8}x+\frac{3}{5}\right|=0\)

=> \(\left|\frac{5}{4}x-\frac{7}{2}\right|-0=\left|\frac{5}{8}x+\frac{3}{5}\right|\)

=> \(\frac{\left|5x-14\right|}{4}=\frac{\left|25x+24\right|}{40}\)

=> \(\frac{10(\left|5x-14\right|)}{40}=\frac{\left|25x+24\right|}{40}\)

=> \(\left|50x-140\right|=\left|25x+24\right|\)

=> \(\orbr{\begin{cases}50x-140=25x+24\\-50x+140=25x+24\end{cases}}\Rightarrow\orbr{\begin{cases}x=\frac{164}{25}\\x=\frac{116}{75}\end{cases}}\)

c, \(\left|\frac{7}{5}x+\frac{2}{3}\right|=\left|\frac{4}{3}x-\frac{1}{4}\right|\)

=> \(\orbr{\begin{cases}\frac{7}{5}x+\frac{2}{3}=\frac{4}{3}x-\frac{1}{4}\\-\frac{7}{5}x-\frac{2}{3}=\frac{4}{3}x-\frac{1}{4}\end{cases}}\)

=> \(\orbr{\begin{cases}x=-\frac{55}{4}\\x=-\frac{25}{164}\end{cases}}\)

Bài 2 : a. |2x - 5| = x + 1

TH1 : 2x - 5 = x + 1

=> 2x - 5 - x = 1

=> 2x - x - 5 = 1

=> 2x - x = 6

=> x = 6

TH2 : -2x + 5 = x + 1

=> -2x + 5 - x = 1

=> -2x - x + 5 = 1

=> -3x = -4

=> x = 4/3

Ba bài còn lại tương tự

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JP

Jenny phạm

24 tháng 10 2018 - olm

Bài 10

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

b) B = \(\frac{3}{2\left(3x-1\right)^4+3\left|y-1\right|^3+2}\)

c) C = \(\frac{1}{2\left(x-\frac{1}{2}\right)^2+3}\)

d) D = \(\frac{x+1}{\left|x\right|}với\left(x\in Z\right)\)

#Toán lớp 7

0

DT

do thi phuong anh

21 tháng 1 2017 - olm

tìm x

a) \(\frac{3}{4}+\frac{1}{4}.x=\frac{1}{2}+\frac{1}{2}.x\)

b) \(\frac{1}{3}.x-\frac{2}{5}.\left(x+1\right)=0\)

c)\(\left(\frac{1}{4}.x-1,5\right)+\left(\frac{5}{6}.x-3\right)-\left(\frac{5}{8}.x-0,5\right)=-4,5\)

#Toán lớp 7

1

NT

Nguyễn Thị Huyền Trang

21 tháng 1 2017

a) \(\frac{3}{4}+\frac{1}{4}.x=\frac{1}{2}+\frac{1}{2}x\)

\(\Rightarrow3.\frac{1}{4}+\frac{1}{4}.x=\frac{1}{2}.\left(x+1\right)\)

\(\Rightarrow\frac{1}{4}.\left(x+3\right)=\frac{1}{2}.\left(x+1\right)\)

\(\Rightarrow\frac{x+1}{x+3}=\frac{1}{4}:\frac{1}{2}=\frac{1}{2}\)\(\Rightarrow\left(x+1\right).2=x+3\Rightarrow2x+2=x+3\)

\(\Rightarrow2x-x=3-2\Rightarrow x=1\)

vay x=1

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NT

Nguyen thanh binh

3 tháng 10 2016

\(a,\left|x-\frac{2}{5}\right|=0,5-\left(-\frac{1}{2}\right)\)

\(b,\frac{3}{2}\left|\frac{1}{4}-x\right|=\frac{5}{6}-1\)

\(c,\frac{4}{3}-\frac{5}{3}\left|x-\frac{1}{3}\right|=-\frac{1}{6}\div\frac{2}{3}\)

#Toán lớp 7

1

IM

Isolde Moria

3 tháng 10 2016

a)

\(\Rightarrow\left|x-\frac{2}{5}\right|=1\)

\(\Rightarrow\left[\begin{array}{nghiempt}x-\frac{2}{5}=1\\x-\frac{2}{5}=-1\end{array}\right.\)\(\Rightarrow\left[\begin{array}{nghiempt}x=\frac{3}{5}\\x=-\frac{3}{5}\end{array}\right.\)

b)

\(\Rightarrow\frac{3}{2}\left|\frac{1}{4}-x\right|=-\frac{1}{6}\)

Mặt khác vì \(\left|\frac{1}{4}-x\right|\ge0\)

\(\Rightarrow\frac{3}{2}.\left|\frac{1}{4}-x\right|\ge0\)

=> \(x\in\varnothing\)

c)

\(\Rightarrow\frac{4}{3}-\frac{5}{3}.\left|x-\frac{1}{3}\right|=-1\)

\(\Rightarrow\frac{5}{3}.\left|x-\frac{1}{3}\right|=\frac{7}{3}\)

\(\Rightarrow\left|x-\frac{1}{3}\right|=\frac{7}{5}\)

\(\Rightarrow\left[\begin{array}{nghiempt}x-\frac{1}{3}=\frac{7}{5}\\x-\frac{1}{3}=-\frac{7}{5}\end{array}\right.\)\(\Rightarrow\left[\begin{array}{nghiempt}x=\frac{26}{15}\\x-\frac{16}{15}\end{array}\right.\)

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LV

Lê Vương Đạt

14 tháng 3 2020 - olm

Bài 1:tính giá trị biểu thức sau:\(B=\left(1-\frac{1}{21}\right).\left(1-\frac{1}{28}\right).\left(1-\frac{1}{36}\right)...\left(1-\frac{1}{1326}\right)\) Bài 2 tìm x...

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#Toán lớp 6

0

M

Mèo_Hanna

18 tháng 10 2018 - olm

Bài 1: Thực hiện phép tính:a, \(3\frac{1}{2}-\frac{1}{2}.\left(-4,25-\frac{3}{4}\right)^2:\frac{5}{4}\)b, \(\frac{3}{7}.1\frac{1}{2}+\frac{3}{7}.0,5-\frac{3}{7}.9\)c, \(\frac{125^{2016}.8^{2017}}{50^{2017}.20^{2018}}\)d, \(\frac{4^{2002}.9^{1001}}{16^{1001}.3^{2003}}\)e, \(\sqrt{25-16}-\left|-3,7+0,7\right|\)Bài 2: Tìm xa, \(\frac{1}{3}x+\frac{4}{5}=3\frac{4}{5}\)b, \(\left|x+\frac{3}{4}\right|-2,25=1\frac{3}{4}\)c, \(\left(-x+\frac{2}{5}\right)^4=\frac{1}{16}\)d,...

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#Toán lớp 7

2

KS

kudo shinichi

18 tháng 10 2018

\(3\frac{1}{2}-\frac{1}{2}.\left(-4,25-\frac{3}{4}\right)^2:\frac{5}{4}\)

\(=\frac{7}{2}-\frac{1}{2}.\left(-4,25-0,75\right)^2:\frac{5}{4}\)

\(=\frac{7}{2}-\frac{1}{2}.\left(-5\right)^2:\frac{5}{4}\)

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

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

\(=\frac{7}{2}-\frac{4}{2}\)

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

\(\frac{3}{7}.1\frac{1}{2}+\frac{3}{7}.0,5-\frac{3}{7}.9\)

\(=\frac{3}{7}.\left(\frac{3}{2}+\frac{1}{2}-9\right)\)

\(=\frac{3}{7}.\left(2-9\right)\)

\(=\frac{3}{7}.\left(-7\right)\)

\(=-3\)

\(\frac{125^{2016}.8^{2017}}{50^{2017}.20^{2018}}=\frac{\left(5^3\right)^{2016}.\left(2^3\right)^{2017}}{\left(5^2\right)^{2017}.2^{2017}.\left(2^2\right)^{2018}.5^{2018}}=\frac{\left(5^3\right)^{2016}.\left(2^3\right)^{2017}}{\left(5^3\right)^{2017}.\left(2^3\right)^{2017}.2.5}=\frac{1}{5^4.2}=\frac{1}{1250}\)( tính nhẩm, ko chắc đúng )

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YM

Yuki Min JinWon

18 tháng 10 2018

1

a) \(3\frac{1}{2}-\frac{1}{2}\cdot\left(-4,25-\frac{3}{4}\right)^2\) : \(\frac{5}{4}\)

= \(3\cdot25:\frac{5}{4}\)

= \(3\cdot\left(25:\frac{5}{4}\right)\)

=\(3\cdot20\)

=60

b)=\(\frac{3}{7}\cdot\left(1\frac{1}{2}+0,5-9\right)\)

=\(\frac{3}{7}\cdot\left(-7\right)\)