Bài1:Tìm x1 .\(3^{2x 2}\)=\(9^{10}\)2. \(7.4^x\)= \(7.4^3\)3. \(\left(\frac{1}{6}\right)^x\)=\(\left(\frac{1}{8}\right)^6\)4. ...

#Toán lớp 7

6

H

headsot96

23 tháng 7 2019

1.\(3^{2x+2}=9^{10}=>3^{2x+2}=3^{20}=>2x+2=20=>2\left(x+1\right)=20\)

\(=>x+1=10=>x=9\)

Vậy x=9

Hok tốt!

H

headsot96

23 tháng 7 2019

2.\(7.4^x=7.4^3\)

\(=>x=3\)

Vậy x=3

Hok tốt

Giải phương trình: 1. \(\frac{2x+3}{4}-\frac{5x+3}{6}=\frac{3-4x}{12}\) 2. \(\frac{3.\left(2x+1\right)}{4}-1=\frac{15x-1}{10}\) 3. \(\frac{2x-1}{5}-\frac{x-2}{3}=\frac{x+7}{15}\) 4. \(\frac{x+3}{2}-\frac{x-1}{3}=\frac{x+5}{6}+1\) 5. \(\frac{x-4}{5}-\frac{3x-2}{10}-x=\frac{2x-5}{3}-\frac{7x+2}{6}\) 6. \(\frac{\left(x+2\right)\left(x+10\right)}{3}-\frac{\left(x+4\right)\left(x+10\right)}{12}=\frac{\left(x-2\right)\left(x+4\right)}{4}\) 7....

NC

Nguyễn Châu Mỹ Linh

8 tháng 1 2020

1

BA

B.Thị Anh Thơ

8 tháng 1 2020

1.

\(\frac{2x+3}{4}-\frac{5x+3}{6}=\frac{3-4x}{12}\)

\(MC:12\)

Quy đồng :

\(\Rightarrow\frac{3.\left(2x+3\right)}{12}-\left(\frac{2.\left(5x+3\right)}{12}\right)=\frac{3x-4}{12}\)

\(\frac{6x+9}{12}-\left(\frac{10x+6}{12}\right)=\frac{3x-4}{12}\)

\(\Leftrightarrow6x+9-\left(10x+6\right)=3x-4\)

\(\Leftrightarrow6x+9-3x=-4-9+16\)

\(\Leftrightarrow-7x=3\)

\(\Leftrightarrow x=\frac{-3}{7}\)

2.\(\frac{3.\left(2x+1\right)}{4}-1=\frac{15x-1}{10}\)

\(MC:20\)

Quy đồng :

\(\frac{15.\left(2x+1\right)}{20}-\frac{20}{20}=\frac{2.\left(15x-1\right)}{20}\)

\(\Leftrightarrow15\left(2x+1\right)-20=2\left(15x-1\right)\)

\(\Leftrightarrow30x+15-20=15x-2\)

\(\Leftrightarrow15x=3\)

\(\Leftrightarrow x=\frac{3}{15}=\frac{1}{5}\)

Bài 1. Giải các phương trình sau 1) \(\frac{3x+2}{2}-\frac{3x+1}{6}=\frac{5}{3}-2x\) 2) \(\frac{x-3}{5}=6-\frac{1-2x}{3}\) 3) \(2\left(x+\frac{3}{5}\right)=5-\left(\frac{13}{5}+x\right)\) 4) \(\frac{2x+3}{3}=\frac{5-4x}{2}\) 5) \(\frac{5x+3}{12}=\frac{1+2x}{9}\) 6) \(x-\frac{x+1}{3}=\frac{2x+1}{5}\) 7) \(\frac{3\left(x-3\right)}{4}+\frac{4x-10,5}{10}=\frac{3\left(x+1\right)}{5}+6\) 8) \(\frac{2\left(3x+1\right)+1}{4}-5=\frac{2 \left(3x-1\right)}{5}-\frac{3x+2}{10}\) 9)...

NT

Nguyễn Thị Thu Hiền

30 tháng 3 2020

1)2x(25x-4)-(5x-2)(5x+1)=8 / 5)\(2\left(x-2\right)-3\left(3x-1\right)=\left(x-3\right)\) 2)x(4x-3)-(2x-2)(2x-1)=5 / 6)\(\frac{2}{x+1}-\frac{1}{x-2}=\frac{3x-11}{\left(x+1\right)\left(x-2\right)}\) 3)\(\frac{5}{2x+3}+\frac{3}{9-x^2}=\frac{8}{7\left(x=3\right)}\) / 7)\(\frac{5x-2}{6}+\frac{3-4x}{2}=2-\frac{x+7}{3}\) 4)\(\frac{2}{3\left(x-2\right)}+\frac{5}{12-3x^2}=\frac{3}{4\left(x+2\right)}\) /...

0

TX

Trần Xuân Mai

7 tháng 8 2016

Tìm x biết:

\(\left(2x+\frac{1}{3}\right)\left(\frac{3}{4}x-6\right)-\left(3x-\frac{2}{3}\right)\left(\frac{1}{2}x-\frac{6}{9}\right)=1\)

#Toán lớp 6

0

KN

Kẹo Ngọt Cây

15 tháng 4 2020

#Toán lớp 10

1

KN

Kẹo Ngọt Cây

15 tháng 4 2020

Đây là lớp 8 nha các b giúp mk với

Do mk viết nhầm

NT

Nguyễn Thị Ngọc Anh

11 tháng 3 2020

1. \(\frac{7}{8}x-5\left(x-9\right)=\frac{20x+1,5}{6}\)

2 . \(\frac{\left(2x+1\right)^2}{5}-\frac{\left(x+1\right)^2}{3}=\frac{7x^2-14x-5}{15}\)

3 . \(4\left(3x-2\right)-3\left(x-4\right)=7x+10\)

4. \(\frac{\left(x+10\right)\left(x+4\right)}{12}-\frac{\left(x+4\right)\left(2-x\right)}{4}=\frac{\left(x+10\right)\left(x-2\right)}{3}\)

2

EC

Edogawa Conan

11 tháng 3 2020

1) \(\frac{7}{8}x-5\left(x-9\right)=\frac{20x+1,5}{6}\)

<=> \(\frac{21x}{24}-\frac{100\left(x-9\right)}{24}=\frac{80x+6}{24}\)

<=> 21x - 100x + 900 = 80x + 6

<=> -79x - 80x = 6 - 900

<=> -159x = -894

<=> x = 258/53

Vậy S = {258/53}

2) \(\frac{\left(2x+1\right)^2}{5}-\frac{\left(x+1\right)^2}{3}=\frac{7x^2-14x-5}{15}\)

<=> \(\frac{3\left(4x^2+4x+1\right)}{15}-\frac{5\left(x^2+2x+1\right)}{15}=\frac{7x^2-14x-5}{15}\)

<=> 12x² + 12x + 3 - 5x² - 10x - 5 = 7x² - 14x - 5

<=> 7x² + 2x - 7x² + 14x = -5 + 2

<=> 16x = 3

<=> x = 3/16

Vậy S = {3/16}

EC

Edogawa Conan

11 tháng 3 2020

3) 4(3x - 2) - 3(x - 4) = 7x+ 10

<=> 12x - 8 - 3x + 12 = 7x + 10

<=> 9x - 7x = 10 - 4

<=> 2x = 6

<=> x = 3

Vậy S = {3}

4) \(\frac{\left(x+10\right)\left(x+4\right)}{12}-\frac{\left(x+4\right)\left(2-x\right)}{4}=\frac{\left(x+10\right)\left(x-2\right)}{3}\)

<=> \(\frac{x^2+14x+40}{12}+\frac{3\left(x^2+2x-8\right)}{12}=\frac{4\left(x^2+8x-20\right)}{12}\)

<=> x² + 14x + 40 + 3x² + 6x - 24 = 4x² + 32x - 80

<=> 4x² + 20x - 4x² - 32x = -80 - 16

<=> -12x = -96

<=> x = 8

Vậy S = {8}

bài1: tìm x:a)\(8< 2^x< =2^9.2^5\)b)\(27< 81^3:3^x< 243\)c)\(\left(\frac{2}{5}\right)^x\left(\frac{5}{2}\right)^{-3}.\left(\frac{-2}{5}\right)^2\)d)\(\left(5x+1\right)^2=\frac{36}{49}\)e)\(\left(x-\frac{2}{9}\right)^3=\left(\frac{2}{3}\right)^6\) f)\(\left(8x-1\right)^{2n+1}=5^{2n+1}\)(n thuộc N)bài 2:tìm x,y biết:a)\(x^2+\left(y-\frac{1}{10}\right)^4=0\)b)\(\left(\frac{1}{2}x-5\right)^{20}+\left(y^2-\frac{1}{4}\right)^{10}<...

LK

Lê Kim Huệ

22 tháng 10 2019

#Toán lớp 7

1

NP

Nguyễn Phương Quỳnh Chi

22 tháng 10 2019

1.

a) \(x\in\left\{4;5;6;7;8;9;10;11;12;13\right\}\)

b) x=0

d) \(x=\frac{-1}{35}\) hoặc \(x=\frac{-13}{35}\)

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

Giúp mk vs đg cần gấp nha cảm ơn mấy bạn nhiều lắm !!!\(\left(\frac{1}{2}\right)^5.x=\left(\frac{1}{2}\right)^7\)\(\left(\frac{3}{7}\right)^2.x=\left(\frac{9}{21}\right)^2\)Bài tìm x biết...

TL

Trần Lưu Gia Ngân

22 tháng 9 2016

#Toán lớp 7

5

YD

_ Yuki _ Dễ thương _

22 tháng 9 2016

nhiều quá trời, lm chắc mỏi tay luôn

NT

Nguyễn Thùy Linh

23 tháng 9 2016

\(\left(\frac{1}{2}\right)^5\times x=\left(\frac{1}{2}\right)^7\)

\(x=\left(\frac{1}{2}\right)^7\div\left(\frac{1}{2}\right)^5\)

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

\(\left(\frac{3}{7}\right)^2\times x=\left(\frac{9}{21}\right)^2\)

\(\left(\frac{3}{7}\right)^2\times x=\left(\frac{3}{7}\right)^4\)

\(x=\left(\frac{3}{7}\right)^4\div\left(\frac{3}{7}\right)^2\)

\(x=\left(\frac{3}{7}\right)^{4-2}=\left(\frac{3}{7}\right)^2=\frac{9}{49}\)

\(2^x=2\Rightarrow x=1\)

\(3^x=3^4\Rightarrow x=4\)

\(7^x=7^7\Rightarrow x=7\)

\(\left(-3\right)^x=\left(-3\right)^5\Rightarrow x=5\)

\(\left(-5\right)^x=\left(-5\right)^4\Rightarrow x=4\)

\(2^x=4\Leftrightarrow2^x=2^2\Rightarrow x=2\)

\(2^x=8\Leftrightarrow2^x=2^3\Rightarrow x=3\)

\(2^x=16\Leftrightarrow2^x=2^4\Rightarrow x=4\)

\(3^{x+1}=3^2\Leftrightarrow x+1=2\Leftrightarrow x=2-1\Rightarrow x=1\)

\(5^{x-1}=5\Leftrightarrow x-1=1\Leftrightarrow x=1+1\Rightarrow x=2\)

\(6^{x+4}=6^{10}\Leftrightarrow x+4=10\Leftrightarrow x=10-4\Rightarrow x=6\)

\(5^{2x-7}=5^{11}\Leftrightarrow2x-7=11\Leftrightarrow2x=11+7\Leftrightarrow2x=18\Leftrightarrow x=18\div2\Rightarrow x=9\)

\(\left(-2\right)^{4x+2}=64\)

\(2^{-4x+2}=2^6\Leftrightarrow-4x+2=6\Leftrightarrow-4x=6-2\Leftrightarrow-4x=4\Leftrightarrow x=4\div\left(-4\right)\Rightarrow x=-1\)

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

\(\left(\frac{5}{6}\right)^{2x}=\left(\frac{5}{6}\right)^5\Rightarrow2x=5\Rightarrow x=\frac{5}{2}\)

\(\left(\frac{3}{4}\right)^{2x-1}=\left(\frac{3}{4}\right)^{5x-4}\Rightarrow2x-1=5x-4\)

\(2x-5x=-4+1\)

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

\(\left(\frac{-1}{10}\right)^x=\frac{1}{100}\)

\(\left(\frac{1}{10}\right)^{-x}=\left(\frac{1}{10}\right)^2\Rightarrow-x=2\Rightarrow x=-2\)

\(\left(\frac{-3}{2}\right)^x=\frac{9}{4}\)

\(\left(\frac{3}{2}\right)^{-x}=\left(\frac{3}{2}\right)^2\Rightarrow-x=2\Rightarrow x=-2\)

\(\left(\frac{-3}{5}\right)^{2x}=\frac{9}{25}\)

\(\left(\frac{3}{5}\right)^{-2x}=\left(\frac{3}{5}\right)^2\Rightarrow-2x=2\Rightarrow x=-1\)

\(\left(\frac{-2}{3}\right)^x=\frac{-8}{27}\)

\(\left(\frac{-2}{3}\right)^x=\left(\frac{-2}{3}\right)^3\Rightarrow x=3\).

hehe. đánh tới què tay, hoa mắt lun r nekkk!!

H

Hiền

25 tháng 9 2017

tính(rút gọn)

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

b,\(\left(2x-4-\frac{x-12}{3x+4}\right)\left(3x-2-\frac{10}{2x+1}\right)\)

c,\(\left(2x-8-\frac{x+10}{3x+1}\right)\left(x-6-\frac{x-6}{3x+2}\right)\)

d,\(\left(1+\frac{1}{x}\right):\left(1-\frac{1}{x^2}\right)\)

0

K

KAl(SO4)2·12H2O

13 tháng 2 2020

a) \(\frac{7x}{8}-5\left(x-9\right)=\frac{20x+1,5}{6}\)

b) \(\frac{5\left(x-1\right)+2}{6}-\frac{7x-1}{4}=\frac{2\left(2x+1\right)}{7}-5\)

c) \(\frac{3\left(x-3\right)}{4}+\frac{4x-10,5}{10}=\frac{3\left(x+1\right)}{5}+6\)

d) \(\frac{2\left(3x+1\right)+1}{4}-5=\frac{2\left(3x-1\right)}{5}-\frac{3x+2}{10}\)

3

K

KAl(SO4)2·12H2O

13 tháng 2 2020

Giải phương tình nha :v

LT

Lê Tài Bảo Châu

13 tháng 2 2020

a) \(\frac{7x}{8}-5\left(x-9\right)=\frac{20x+1,5}{6}\)

\(\Leftrightarrow\frac{7x}{8}-\frac{40\left(x-9\right)}{8}=\frac{20x+1,5}{6}\)

\(\Leftrightarrow\frac{7x}{8}-\frac{40x-360}{8}=\frac{20x+1,5}{6}\)

\(\Leftrightarrow\frac{360-33x}{8}=\frac{20x+1,5}{6}\)

\(\Leftrightarrow2160-198x=160x+12\)

\(\Leftrightarrow358x=2148\)

\(\Leftrightarrow x=6\)

Vậy nghiệm của pt x=6

b) \(\frac{5\left(x-1\right)+2}{6}-\frac{7x-1}{4}=\frac{2\left(2x+1\right)}{7}-5\)

\(\Leftrightarrow\frac{10\left(x-1\right)+4}{12}-\frac{21x-3}{12}=\frac{4x+2}{7}-\frac{35}{7}\)

\(\Leftrightarrow\frac{-11x-3}{12}=\frac{4x-33}{7}\)

\(\Leftrightarrow-77x-21=48x-396\)

\(\Leftrightarrow125x=375\)

\(\Leftrightarrow3\)

Vậy nghiệm của pt x=3