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S
0
PL
1
DN
9 tháng 8 2018
x^200+x^100+1=x^100*(x^2+1)+1
x^4+x^2+1=x^2*(x^2+1)+1
mà x^100chia hết cho x^2
x^2+1chia hết cho x^2+1
1 chia hết cho1
suy ra x^100*(x^2+1)+1 chia hết cho x^2*(x^2+1)+1 hay x^200+x^100+1 chia hết cho x^4+x^2+1
0N
1
2 tháng 9 2018
\(A=x^{200}+x^{100}+1\)
\(=x^{200}-x^2+x^{100}-x^4+x^4+x^2+1\)
\(=x^2\left(x^{198}-1\right)+x^4\left(x^{96}-1\right)+\left(x^4+x^2+1\right)\)
\(=x^2\left(x^{^6}-1\right).A+x^4\left(x^6-1\right).B+x^4+x^2+1\)
\(x^6-1=\left(x^3-1\right)\left(x^3+1\right)=\left(x-1\right)\left(x^2+x+1\right)\left(x+1\right)\left(x^2-x+1\right)=\left(x-1\right)\left(x+1\right)\left(x^4+x^2+1\right)\)
Vậy \(A⋮\left(x^4+x^2+1\right)\)
ND
7 tháng 7 2018
1)
\(\dfrac{x-5}{100}+\dfrac{x-4}{101}+\dfrac{x-3}{102}=\dfrac{x-100}{5}+\dfrac{x-101}{4}+\dfrac{x-102}{3}\)
\(\Leftrightarrow\dfrac{x-5}{100}+1+\dfrac{x-4}{101}+1+\dfrac{x-3}{102}+1=\dfrac{x-100}{5}+1+\dfrac{x-101}{4}+1+\dfrac{x-102}{3}+1\)
\(\Leftrightarrow\dfrac{x-105}{100}+\dfrac{x-105}{101}+\dfrac{x-105}{102}=\dfrac{x-105}{5}+\dfrac{x-105}{4}+\dfrac{x-105}{3}+\dfrac{x-105}{2}\)
\(\Leftrightarrow\dfrac{x-105}{100}+\dfrac{x-105}{101}+\dfrac{x-105}{102}-\dfrac{x-105}{5}-\dfrac{x-105}{4}-\dfrac{x-105}{3}-\dfrac{x-105}{2}=0\)
\(\Leftrightarrow\left(x-105\right)\left(\dfrac{1}{100}+\dfrac{1}{101}+\dfrac{1}{102}-\dfrac{1}{5}-\dfrac{1}{4}-\dfrac{1}{3}-\dfrac{1}{2}\right)=0\)\(\Leftrightarrow105-x=0\)
\(\Leftrightarrow x=105\)
b)
\(\dfrac{29-x}{21}+\dfrac{27-x}{23}+\dfrac{25-x}{25}+\dfrac{23-x}{27}+\dfrac{21-x}{29}=0\)
\(\Leftrightarrow\dfrac{29-x}{21}+1+\dfrac{27-x}{23}+1+\dfrac{25-x}{25}+1+\dfrac{23-x}{27}+1+\dfrac{21-x}{29}+1=0\)
\(\Leftrightarrow\dfrac{50-x}{21}+\dfrac{50-x}{23}+\dfrac{50-x}{25}+\dfrac{20-x}{27}+\dfrac{50-x}{29}=0\)
\(\Leftrightarrow\left(50-x\right)\left(\dfrac{1}{21}+\dfrac{1}{23}+\dfrac{1}{25}+\dfrac{1}{27}+\dfrac{1}{29}\right)=0\)
\(\Leftrightarrow50-x=0\)
\(\Leftrightarrow x=50\)
ND
7 tháng 7 2018
2)
\(\left(5x+1\right)^2=\left(3x-2\right)^2\)
\(\Leftrightarrow\left|5x+1\right|=\left|3x-2\right|\)
\(\Leftrightarrow\left[{}\begin{matrix}5x+1=3x-2\\5x+1=-3x+2\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{-3}{2}\\x=\dfrac{1}{8}\end{matrix}\right.\)
b) \(\left(x+2\right)^3=\left(2x+1\right)^3\)
\(\Leftrightarrow x^3+6x^2+12x+8=8x^3+12x^2+6x+1\)
\(\Leftrightarrow-7x^3-6x^2+6x+7=0\)
\(\Leftrightarrow-7x^3+7x^2-13x^2+13x-7x+7=0\)
\(\Leftrightarrow-7x^2\left(x-1\right)-13x\left(x-1\right)-7\left(x-1\right)=0\)
\(\Leftrightarrow\left(x-1\right)\left(-7x^2-13x-7\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\-7x^2-13x-7=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\-7\left(x^2+\dfrac{13}{7}x+1\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\-7\left(x+\dfrac{13}{14}\right)^2-\dfrac{169}{196}=0\left(l\right)\end{matrix}\right.\)
\(\Leftrightarrow x=1\)
4 tháng 9 2018
a) \(\Leftrightarrow\left(2x+1\right)^3-125=0\)
\(\Leftrightarrow\left(2x+1-5\right)\left(4x^2+4x+1+10x+5+5\right)=0\)
\(=\left(2x-4\right)\left(4x^2+14x+11\right)=0\)
\(4x^2+14x+11>0\Leftrightarrow x=2\)
b) \(\Leftrightarrow\left(x+1\right)^2-64=0\Leftrightarrow\left(x+1+8\right)\left(x+1-8\right)=0\)
\(\Leftrightarrow\left(x+9\right)\left(x-7\right)=0\Leftrightarrow\left[{}\begin{matrix}x=-9\\x=7\end{matrix}\right.\)
c) \(x^2+2x+4^x-2^{x+1}+2=0\)
\(\Leftrightarrow\left(x+1\right)^2+\left(4^x-2^{x+1}+1\right)=0\)
\(\Leftrightarrow\left(x+1\right)^2+\left(2^x-1\right)^2=0\)
x=-1;0 suy ra pt vô nghiệm
AH
Akai Haruma
Giáo viên
4 tháng 9 2018
Lời giải:
a) \((2x+1)^3-25=100\)
\(\Rightarrow (2x+1)^3=125=5^3\)
\(\Rightarrow 2x+1=5\Rightarrow x=2\)
b)
\((x+1)^2-4=60\)
\(\Leftrightarrow (x+1)^2=64\)
\(\Rightarrow \left[\begin{matrix} x+1=\sqrt{64}=8\\ x+1=-\sqrt{64}=-8\end{matrix}\right.\Rightarrow \left[\begin{matrix} x=7\\ x=-9\end{matrix}\right.\)
c)
\(x^2+2x+4^x-2^{x+1}+2=0\)
\(\Leftrightarrow (x^2+2x+1)+(4^x-2^{x+1}+1)=0\)
\(\Leftrightarrow (x+1)^2+(2^x-1)^2=0\)
Vì \((x+1)^2; (2^x-1)^2\geq 0\Rightarrow \) để tổng của chúng bằng 0 thì:
\(\left\{\begin{matrix} (x+1)^2=0\\ (2^x-1)^2=0\end{matrix}\right.\Leftrightarrow \left\{\begin{matrix} x=-1\\ x=0\end{matrix}\right.\) (vô lý)
Do đó pt vô nghiệm
22 tháng 6 2022
b: \(\Leftrightarrow\left(\dfrac{29-x}{21}+1\right)+\left(\dfrac{27-x}{23}+1\right)+\left(\dfrac{25-x}{25}+1\right)+\left(\dfrac{23-x}{27}+1\right)+\left(\dfrac{21-x}{29}+1\right)=0\)
=>50-x=0
hay x=50
c: \(\Leftrightarrow\dfrac{x-2}{2001}+1=\dfrac{x-1}{2002}+\dfrac{x}{2003}\)
\(\Leftrightarrow\left(\dfrac{x-2}{2001}-1\right)=\left(\dfrac{x-1}{2002}-1\right)+\left(\dfrac{x}{2003}-1\right)\)
=>x-2003=0
hay x=2003
đề đâu
chứng minh chia hết thì phải