Bài 1 : Tìm n :A) \(\frac{1}{2}x2^n 4x2^n=9x5^n\)B)\(3x\left(2^n 1\right) 5x\left(2^n\right)=72\)C)\(\frac{1}{9}x27^n3^n\)D)\(32

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K

Kaijo

6 tháng 5 2020

1,Giải PT sau

a,(x-1)²+(x+3)²=2(x-2)(x+1)+38

b,5(x²-2x-1)+2(3x-2)=5(x+1)²

c,(x-3)³-2(x-1)=x(x-2)²-5x²

d,x(x+3)²-3x=(x+2)³+1

e,\\(\\frac{\\left(x-1\\right)\\left(x+5\\right)}{3}-\\frac{\\left(x+2\\right)\\left(x+5\\right)}{12}=\\frac{\\left(x-1\\right)\\left(x+2\\right)}{4}\\)

\n

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K

Kaijo

6 tháng 5 2020

lỗi j ạ

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\n

NM

Nguyễn Minh Phương

4 tháng 12 2016

B1 Tính

\(\frac{x^3+125}{3x-9}.\frac{3-x}{x^2-5x+25}\)

B2 : Cho abc = 1. Tính M-N

\(M=\left(a+\frac{1}{a}\right)^2\left(b+\frac{1}{b}\right)^2+\left(c+\frac{1}{c}\right)2\)

\(N=\left(a+\frac{1}{a}\right)\left(b+\frac{1}{b}\right)\left(c+\frac{1}{c}\right)\)

1. Tìm giá trị của x để các phân thức sau bằng 0 a. \(\frac{x^4+x^3+x+1}{x^4-x^3+2x^2-x+1}\)b. \(\frac{x^4-5x^2+4}{x^4-10x^2+9}\)2. Rút gọn các phân thức:a. \(\frac{3x^3-7x^2+5x-1}{2x^3-x^2-4x+3}\) b. \(\frac{\left(x-y\right)^3-3xy\left(x+y\right)+y^{^3}}{x-6y}\)3. Rút gọn các phân thức với n là số tự nhiên a. \(\frac{\left(n+1\right)!}{n!\left(n+2\right)}\) b. \(\frac{n!}{\left(n+1\right)!-n!}\) ...

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D

demilavoto

29 tháng 10 2015

Tính tổng :a) \(A=\frac{5}{2\cdot1}+\frac{4}{1\cdot11}+\frac{3}{11\cdot14}+\frac{1}{14\cdot15}+\frac{13}{15\cdot28}\)b) \(B=\frac{-1}{20}+\frac{-1}{30}+\frac{-1}{42}+\frac{-1}{56}+\frac{-1}{72}+\frac{-1}{90}\)c) \(C=\frac{1}{1\cdot2\cdot3}+\frac{1}{2\cdot3\cdot4}+...+\frac{1}{n\left(n+1\right)\left(n+2\right)}\)d) \(D=\frac{1}{1\cdot2\cdot3\cdot4}+\frac{1}{2\cdot3\cdot4\cdot5}+...+\frac{1}{n\left(n+1\right)\left(n+2\right)\left(n+3\right)}\)e)...

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YA

Yukki Asuna

7 tháng 2 2017

Tính tổng : a) \(A=\frac{5}{2\cdot1}+\frac{4}{1\cdot11}+\frac{3}{11\cdot14}+\frac{1}{14\cdot15}+\frac{13}{15\cdot28}\) b) \(B=\frac{-1}{20}+\frac{-1}{30}+\frac{-1}{42}+\frac{-1}{56}+\frac{-1}{72}+\frac{-1}{90}\) c) \(C=\frac{1}{1\cdot2\cdot3}+\frac{1}{2\cdot3\cdot4}+...+\frac{1}{n\left(n+1\right)\left(n+2\right)}\) d) \(D=\frac{1}{1\cdot2\cdot3\cdot4}+\frac{1}{2\cdot3\cdot4\cdot5}+...+\frac{1}{n\left(n+1\right)\left(n+2\right)\left(n+3\right)}\) e)...

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KK

Kirigaya Kazuto

7 tháng 2 2017

1

HH

Hoang Hung Quan

7 tháng 2 2017

\(A=\frac{5}{2.1}+\frac{4}{1.11}+\frac{3}{11.14}+\frac{1}{14.15}+\frac{13}{15.28}\)

\(\frac{A}{7}=\frac{5}{2.7}+\frac{4}{7.11}+\frac{3}{11.14}+\frac{1}{14.15}+\frac{13}{15.28}\)

\(\frac{A}{7}=\frac{7-2}{2.7}+\frac{11-7}{7.11}+\frac{14-11}{11.4}+\frac{15-14}{14.15}+\frac{28-15}{15.28}\)

\(\frac{A}{7}=\frac{1}{2}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+\frac{1}{14}-\frac{1}{15}+\frac{1}{15}-\frac{1}{28}=\frac{1}{2}-\frac{1}{28}=\frac{13}{28}\)

\(A=7.\frac{13}{28}\)

\(A=\frac{13}{4}\)

Bài 3 Tìm nguyên số \(n\)\(\frac{1}{9}x27^n=3^n\)\(3^{-2}x3^4x3^n=3^7\)\(2^{-1}x2^n+4x2^n=9x2^5\)\(32^{-n}x16^n=2048\)Bài 4 : Tìm...

TP

Thảo Phạm

9 tháng 6 2015

Bài 2a) \(A=\left(\frac{1}{2}-1\right)\left(\frac{1}{3}-1\right)...\left(\frac{1}{2002}-1\right)\left(\frac{1}{2003}-1\right)\)b) \(B=\left(-1\frac{1}{2^2}\right)\left(-1\frac{1}{3^2}\right)\left(-1\frac{1}{4^2}\right)...\left(-1\frac{1}{2003^2}\right)\left(-1\frac{1}{2004^2}\right)\)c) \(C=\left(1-\frac{1}{2^2}\right)\left(1-\frac{1}{3^2}\right)\left(1-\frac{1}{4^2}\right)...\left(1-\frac{1}{n^2}\right)\left(n\in...

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JP

Jenny phạm

23 tháng 8 2018

#Toán lớp 7

1

EC

Edogawa Conan

23 tháng 8 2018

\(A=\left(\frac{1}{2}-1\right)\left(\frac{1}{3}-1\right)...\left(\frac{1}{2002}-1\right)\left(\frac{1}{2003}-1\right)\)

\(=\left(-\frac{1}{2}\right)\left(-\frac{2}{3}\right)...\left(-\frac{2001}{2002}\right)\left(-\frac{2002}{2003}\right)\)

\(=\frac{-1.\left(-2\right).....\left(-2001\right)\left(-2002\right)}{2.3....2002.2003}\)

\(=\frac{1}{2003}\)

T

Tuấn

25 tháng 2 2017

help me! (ngu toàn...

1

LD

l҉o҉n҉g҉ d҉z҉

26 tháng 2 2017

\(\frac{150}{5.8}+\frac{150}{8.11}+\frac{150}{11.14}+.....+\frac{150}{47.50}\)

\(=50.\left(\frac{3}{5.8}+\frac{5}{8.11}+.....+\frac{3}{47.50}\right)\)

\(=50.\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+......+\frac{1}{47}-\frac{1}{50}\right)\)

\(=50.\left(\frac{1}{5}-\frac{1}{50}\right)\)

\(=50.\frac{9}{50}=9\)

Bài 1: Tìm x biết:a. \(\frac{5}{1.6}+\frac{5}{6.11}+...+\frac{5}{\left(5x+1\right)\left(5x+6\right)}=\frac{2010}{2011}\)b. \(\frac{7}{x}+\frac{4}{5.9}+\frac{4}{9.13}+\frac{4}{13.17}+..+\frac{4}{41.45}=\frac{29}{45}\)c. \(1+\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+...+\frac{1}{x\left(x+2\right)}:2\)d. (x-20) . \(\frac{\frac{1}{2}+\frac{1}{3}+..+\frac{1}{2000}}{\frac{1}{199}+\frac{2}{198}+\frac{3}{197}+...+\frac{198}{2}+\frac{199}{1}}=\frac{1}{2000}\)Bài...

TL

Thảo Lê Phương

13 tháng 5 2017

2

KT

♨❤♨~Koo ๖ۣۜϑũ❥꧁şɦυυ꧂❣ ♫✔♫

13 tháng 5 2017

tung từng vế một thôi

bạn nhác quá éo chịu suy nghĩ

bài này dễ vl

S

ST

13 tháng 5 2017

Bài 1:

a, \(\frac{5}{1.6}+\frac{5}{6.11}+...+\frac{5}{\left(5x+1\right)\left(5x+6\right)}=\frac{2010}{2011}\)

\(1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+...+\frac{1}{5x+1}-\frac{1}{5x+6}=\frac{2010}{2011}\)

\(1-\frac{1}{5x+6}=\frac{2010}{2011}\)

\(\frac{1}{5x+6}=1-\frac{2010}{2011}\)

\(\frac{1}{5x+6}=\frac{1}{2011}\)

=> 5x + 6 = 2011

5x = 2011 - 6

5x = 2005

x = 2005 : 5

x = 401

b, \(\frac{7}{x}+\frac{4}{5.9}+\frac{4}{9.13}+...+\frac{4}{41.45}=\frac{29}{45}\)

\(\frac{7}{x}+\left(\frac{4}{5.9}+\frac{4}{9.13}+...+\frac{4}{41.45}\right)=\frac{29}{45}\)

\(\frac{7}{x}+\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+...+\frac{1}{41}-\frac{1}{45}\right)=\frac{29}{45}\)

\(\frac{7}{x}+\left(\frac{1}{5}-\frac{1}{45}\right)=\frac{29}{45}\)

\(\frac{7}{x}+\frac{8}{45}=\frac{29}{45}\)

\(\frac{7}{x}=\frac{29}{45}-\frac{8}{45}\)

\(\frac{7}{x}=\frac{7}{15}\)

=> x = 15

c, ghi lại đề

d, ghi lại đề

Bài 2:

\(\frac{1}{n}-\frac{1}{n+a}=\frac{n+a}{n\left(n+a\right)}-\frac{n}{n\left(n+a\right)}=\frac{a}{n\left(n+a\right)}\)