Ta có :\(\frac{x+8}{12}+\frac{x+9}{11}+\frac{x+10}{10}+3=0\)

=> \(\left(\frac{x+8}{12}+1\right)+\left(\frac{x+9}{11}+1\right)+\left(\frac{x+10}{10}+1\right)=0\)

=> \(\frac{x+20}{12}+\frac{x+20}{11}+\frac{x+20}{10}=0\)

=> \(\left(x+20\right)\left(\frac{1}{12}+\frac{1}{11}+\frac{1}{10}\right)=0\)

Vì \(\frac{1}{12}+\frac{1}{11}+\frac{1}{10}\ne0\)

=> x + 20 = 0

=> x = -20

Vậy x = -20

\(\frac{x+8}{12}+\frac{x+9}{11}+\frac{x+10}{10}+3=0\)

\(\Leftrightarrow\left(\frac{x+8}{12}+1\right)+\left(\frac{x+9}{11}+1\right)+\left(\frac{x+10}{10}+1\right)=0\)

\(\Leftrightarrow\frac{x+20}{12}+\frac{x+20}{11}+\frac{x+20}{10}=0\)

\(\Leftrightarrow\left(x+20\right)\left(\frac{1}{12}+\frac{1}{11}+\frac{1}{10}\right)=0\)

Vì \(\frac{1}{12}+\frac{1}{11}+\frac{1}{10}\ne0\)

\(\Rightarrow x+20=0\Rightarrow x=-20\)

Đề bài yêu cầu gì nhỉ ?

-5.83 ( sai thì xin thông cảm )

Tom must help you with your homework. You musn't do it yourself.

Chúc bạn học tốt!

\(x+2x+3x+4x+10x+50=100\)

\(\Leftrightarrow x\left(1+2+3+4+10\right)+50=100\)

\(\Leftrightarrow x20=50\Leftrightarrow x=\frac{5}{2}\)

x+2x+3x+4x+10x+50=20x+50=100

=> 20x=50

=> \(x=\frac{5}{2}\)

Vậy x=\(\frac{5}{2}\)

Bài làm:

a) đkxđ: \(x\ne\pm1\)

Ta có:

\(M=\frac{x+1}{x^2-1}-\frac{x^2+2}{x^3-1}-\frac{x+1}{x^2+x+1}\)

\(M=\frac{1}{x-1}-\frac{x^2+2}{\left(x-1\right)\left(x^2+x+1\right)}-\frac{x+1}{x^2+x+1}\)

\(M=\frac{x^2+x+1-x^2-2-\left(x+1\right)\left(x-1\right)}{\left(x-1\right)\left(x^2+x+1\right)}\)

\(M=\frac{x-1-x^2+1}{\left(x-1\right)\left(x^2+x+1\right)}\)

\(M=\frac{x\left(1-x\right)}{\left(x-1\right)\left(x^2+x+1\right)}=-\frac{x}{x^2+x+1}\)

b) Mà x khác 1

=> x = -2, khi đó:

\(M=-\frac{-2}{4-2+1}=\frac{2}{3}\)

\(1,75-\left|x\right|=3,21\)

\(\Leftrightarrow\left|x\right|=1,75-3,21\)

\(\Leftrightarrow\left|x\right|=-1,46\) ( Vô lí )

Không tồn tại x thỏa mãn đề.

1,75-|x|=3,21

1,75-x=3,21   hoặc    1,75-x=-3,21

x=1,75-3,21  hoặc   x=1,75+3,21

x=-1,46   hoặc    x=4,96

vậy  x=-1,46  hoặc  4,96

a)

Có:   \(70=2.5.7\)

\(70=2^1.5^1.7^1\)

=>    70 có số ước là:    \(\left(1+1\right)\left(1+1\right)\left(1+1\right)=2.2.2=8\)    (Ước)

b)

Có:   \(117=3^2.13^1\)

=> 117 có số ước là:   \(\left(2+1\right)\left(1+1\right)=3.2=6\)        (Ước)

70=2.5.7

117=3².13

Ư₍₇₀₎=1;2;5;7;10;14;35;70

Ư₍₁₁₇₎=1;3;9;13;39;117

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