Giúp tôi với
( x + 8 ) ⋮ ( x - 1)
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\(A=\left(a\text{x}7+a\text{x}8-a\text{x}15\right):\left(1+2+3+...+10\right)\)
\(A=\left(a\text{x}\left(7+8-15\right)\right):\left(1+2+3+...+10\right)\)
\(A=\left(a\text{x}0\right):\left(1+2+3+..+10\right)\)
\(A=0:\left(1+2+3+...+10\right)\)
\(A=0\)
\(B=\left(18-9\text{x}2\right)\text{x}\left(2+4+6+8+10\right)\)
\(B=\left(18-18\right)\text{x}\left(2+4+6+8+10\right)\)
\(B=0\text{x}\left(2+4+6+8+10\right)\)
\(B=0\)
\(\left\{{}\begin{matrix}x-2y=1\\2x+2y=8\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1+2y\\2\left(1+2y\right)+2y=8\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1+2y\\2+4y+2y=8\end{matrix}\right.\text{}\Leftrightarrow\left\{{}\begin{matrix}x=3\\y=1\end{matrix}\right.\)
Vậy hệ PT đã cho có nghiệm duy nhất \(\left(x;y\right)=\left(3;1\right)\)
\(x\div\frac{1}{2}+x\div\frac{1}{4}+x\div\frac{1}{8}+x=960\)
\(x\times2+x\times4+x\times8+x=960\)
\(x\times\left(2+4+8+1\right)=960\)
\(x\times15=960\)
\(x=960\div15\)
\(x=64\)
HPT: \(\hept{\begin{cases}\frac{1}{x}+\frac{1}{y}=8\\x-y=12\end{cases}}\)
\(\Leftrightarrow\frac{1}{x}+\frac{1}{x-12}=8\)
\(\Leftrightarrow\frac{x-12+x-8x^2+96x}{x^2-12x}=0\)
\(\Leftrightarrow8x^2-98x+12=0\)
\(\Leftrightarrow4x^2-49x+6=0\)
\(\Leftrightarrow4\left(x-\frac{49}{8}\right)^2=\frac{2305}{16}\)
\(\Leftrightarrow x=\pm\frac{\sqrt{2305}+49}{8}\)'
\(\Leftrightarrow\orbr{\begin{cases}x=\frac{49+\sqrt{2305}}{8}\Leftrightarrow y=\frac{-47+\sqrt{2305}}{8}\\x=\frac{49-\sqrt{2305}}{8}\Leftrightarrow y=-\frac{47+\sqrt{2305}}{8}\end{cases}}\)
Kết luận nghiệm .....
p/s : nghiệm xấu quá đi :(((
(1 -1/5) * (1-1/6) *(1-1/7) *(1-1/8)
=4/5 * 5/6* 6/7 *7/8
=1/2
\(\Rightarrow x-1\inƯ\left(9\right)\left\{1;3;9\right\}\\ \Rightarrow x\in\left\{2;4;10\right\}\)
\(\Leftrightarrow x-1\in\left\{1;-1;3;-3;9;-9\right\}\)
hay \(x\in\left\{2;0;4;-2;10;-8\right\}\)