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\(\frac{6}{11}x=\frac{9}{2}y=\frac{18}{5}z\Rightarrow\frac{6x}{11.18}=\frac{9y}{2.18}=\frac{18z}{5.18}\)
\(\Rightarrow\frac{-x}{-33}=\frac{y}{4}=\frac{z}{5}=\frac{-x+y+z}{-33+4+5}=\frac{-120}{-24}=5\)
\(\Rightarrow x=165;y=20;z=25\)
Ta có : \(A=\frac{4x+3}{x-2}=\frac{2\left(x-2\right)+7}{x-2}=2+\frac{7}{x-2}\)
Để \(A\in Z\)thì \(7⋮x-2\)hay x-2 là Ư(7)={1;-1;7;-7}
Do đó:
| x-2 | 1 | -1 | 7 | -7 |
| x | 3 | 1 | 9 | -5 |
Vậy .....
Ta có : \(B=\frac{2x-15}{x+1}=\frac{2\left(x+1\right)-17}{x+1}=2-\frac{17}{x+1}\)
Để \(B\in Z\)thì \(17⋮x+1\)hay x+1 là Ư(17)={1;-1;17;-17}
Do đó :
| x+1 | 1 | -1 | 17 | -17 |
| x | 0 | -2 | 16 | -18 |
Vậy ................
Tự ghi đề nhé!
a. \(\frac{-3}{4}:x=\frac{-11}{36}+\frac{1}{2}\)
= 7/36
x = 7/36 : -3/4 = -7/27
a, \(\left(2x-1\right)^2:9=49\)
\(\left(2x-1\right)^2=441\)
\(\Rightarrow\orbr{\begin{cases}2x-1=441\\2x-1=-441\end{cases}\Rightarrow\orbr{\begin{cases}x=221\\x=-220\end{cases}}}\)
b, \(3^x+3^{x+2}=810\)
\(3^x+3^x.3^2=810\)
\(3^x\left(1+3^2\right)=810\)
\(3^x.10=810\)
\(3^x=81=3^4\)
\(\Rightarrow x=4\)
\(\hept{\begin{cases}80⋮x\\56⋮x\end{cases}}\Rightarrow x\inƯC\left(80;56\right)\)
\(80=2^4.5\)
\(56=2^3.7\)
\(ƯCLN\left(80;56\right)=2^3=8\)
\(\RightarrowƯC\left(80;56\right)=Ư\left(8\right)=\left\{\pm1;\pm2;\pm4;\pm8\right\}\)
Mà \(x\ge3\)
\(\Rightarrow x\in\left\{4;8\right\}\)
a) \(\left(2x-1\right)^2\div9=49\)
\(\Leftrightarrow\left(2x-1\right)^2=49\times9\)
\(\Leftrightarrow\left(2x-1\right)^2=441\)
\(\Leftrightarrow\left(2x-1\right)^2=\left(\pm21\right)^2\)
\(\Leftrightarrow\orbr{\begin{cases}2x-1=21\\2x-1=-21\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=11\\x=-10\end{cases}}\)
Vậy \(x\in\left\{-10;11\right\}\)
b) \(3^x+3^{x+2}=810\)
\(\Leftrightarrow3^x+3^x.3^2=810\)
\(\Leftrightarrow3^x\left(1+3^2\right)=810\)
\(\Leftrightarrow3^x.10=810\)
\(\Leftrightarrow3^x=810\div10\)
\(\Leftrightarrow3^x=81\)
\(\Leftrightarrow3^x=3^5\)
\(\Leftrightarrow x=5\)
Xinloi, t lm nhầm câu a. Lm` giống ๖²⁴ʱŠїêʉ şαø вóηɠ đá"NCTK" nhé :)
\(\frac{2x}{3}-\frac{2}{y}=\frac{1}{3}\)
\(\frac{2}{y}=\frac{2x}{3}-\frac{1}{3}\)
\(\frac{2}{y}=\frac{2x-1}{3}\)
\(\Rightarrow2.3=y\left(2x-1\right)\)
\(\Rightarrow y\left(2x-1\right)=6=1.6=6.1=2.3=3.2=\left(-1\right)\left(-6\right)=\left(-6\right)\left(-1\right)=\left(-2\right)\left(-3\right)=\left(-3\right).\left(-2\right)\)
Tự kẻ bảng nhé :))
P/s: Hoq chắc