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a) Đk : \(x\ne0;\ne1\)
\(\dfrac{x+3}{x+1}+\dfrac{x-2}{x}=\dfrac{2\left(x^2+x-1\right)}{x\left(x+1\right)}\)
\(\Rightarrow\dfrac{x^2+3x}{x\left(x+1\right)}+\dfrac{x^2-x-2}{x\left(x+1\right)}-\dfrac{2x^2+2x-2}{x\left(x+1\right)}=0\)
\(\Rightarrow\dfrac{x^2+3x+x^2-x-2-2x^2-2x+2}{x\left(x-1\right)}=0\)
\(\Rightarrow\dfrac{0}{x-1}=0\)
=> Phương trình có vô số nghiệm x
b) Đk : \(x\ne2;x\ne3\)
\(\dfrac{2}{x-2}-\dfrac{x}{x+3}=\dfrac{5x}{\left(x-2\right)\left(x+3\right)}-1\)
\(\Rightarrow\dfrac{2x+6}{\left(x-2\right)\left(x+3\right)}-\dfrac{x^2-2x}{\left(x-2\right)\left(x+3\right)}-\dfrac{5x}{\left(x-2\right)\left(x+3\right)}+\dfrac{x^2+x-6}{\left(x-2\right)\left(x+3\right)}\)
=0
\(\Rightarrow\dfrac{2x+6-x^2+2x-5x+x^2+x+6}{\left(x-2\right)\left(x+3\right)}=0\)
\(\Rightarrow\dfrac{12}{\left(x-2\right)\left(x+3\right)}=0\)
=> Phương trình vô nghiệm
c)
\(\Leftrightarrow\dfrac{x^2-x+1}{x^4+x^2+1}-\dfrac{x^2+x+1}{x^4+x^2+1}-\dfrac{1-2x}{x^4+x^2+1}=0\)
\(\Rightarrow\dfrac{x^2-x+1-x^2-x-1-1+2x}{x^4+x^2+1}=0\)
\(\Rightarrow\dfrac{-1}{x^4+x^2+1}=0\)
=> PTVN
d) Thôi tự làm đi, câu này dễ :Vvv
e)
\(\left(x+1\right)\left(x+2\right)\left(x+4\right)\left(x+5\right)\)=40
\(\Rightarrow\left[\left(x+1\right)\left(x+5\right)\right]\cdot\left[\left(x+2\right)\left(x+4\right)\right]=40\)
\(\Rightarrow\left(x^2+6x+5\right)\left(x^2+6x+8\right)=40\)
Đặt
\(x^2+6x+7=t\)
Phương trình tương đương
\(\left(t-1\right)\left(t+1\right)=40\)
\(t^2=41\)
\(\)\(t=\pm\sqrt{41}\)
Thay vào tìm x.
a,<=>\(\frac{\left(2x+1\right)^2}{4}\)+\(\frac{2\left(2x-1\right)^2}{4}\)≥\(\frac{12\left(x+5\right)^2}{4}\)
<=>4x2+4x+1+2(4x2-4x+1)≥12(x2+10x+25)
<=>4x2+4x+1+8x2-8x+2≥12x2+120x+300
<=>4x2+4x+1+8x2-8x+2-12x2-120x-300≥0
<=>-124x-297≥0
<=>124x+297≤0
<=>124x≤-297
<=>x≤\(\frac{-297}{124}\)
b, Tương tự câu a
c, |5−3x|=2+x
TH1: 5-3x=2+x
<=> -3x - x = 2 - 5
<=> -4x = -3
<=> x = 3/4
TH2: 5-3x = -2 - x
<=> -3x + x = -2 - 5
<=> -2x = -7
<=> x = 7/2
a) (x+3)4+(x+5)4=16
<=>(x+3)4+(x+5)4=04+24
TH1: \(\left\{{}\begin{matrix}x+3=0\\x+5=2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-3\\x=-3\end{matrix}\right.\Leftrightarrow x=-3\)
TH2:\(\left\{{}\begin{matrix}x+3=2\\x+5=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-1\\x=-5\end{matrix}\right.\)(loại)
b)(x-2)4+(x-3)4=1=04+14
TH1: \(\left\{{}\begin{matrix}x-2=0\\x-3=1\end{matrix}\right.\)loại
TH2: \(\left\{{}\begin{matrix}x-2=1\\x-3=0\end{matrix}\right.\)=>x=3.
c)(x+1)4+(x-3)4=82=34+(-1)4
làm tương tự => x=2.
d) làm tương tự câu b
a)\(\left(x^4+8x^2+16\right):\left(x^2+4\right)\)
\(=\left(x^2+4\right)^2:\left(x^2+4\right)\)
\(=x^2+4\)
b)\(\left(25-x^2\right):\left(x+5\right)\)
=\(\left(x^2-5^2\right):\left(x+5\right)\)
\(=\left(x-5\right)\left(x+5\right):\left(x+5\right)\)
\(=x-5\)
c)\(\left(x^3+1\right):\left(x^2-x+1\right)\)
\(=\left(x+1\right)\left(x^2-x+1\right):\left(x^2-x+1\right)\)
\(=x+1\)
a) \(\left(x^4+8x^2+16\right):\left(x^2+4\right)\)\(=\left(x^2+4\right)^2:\left(x^2+4\right)\)\(=x^2+4\)
b) \(\left(25-x^2\right):\left(x+5\right)=\left(x-5\right).\left(x+5\right):\left(x+5\right)\)\(=x-5\)
c) \(=\left(x^3+1\right)\left(x^2-x+1\right)=\left(x+1\right)\left(x^2-x+1\right)\)\(=x+1\)
Học tốt
a) <=> \(A=\left(3^2-1\right)\left(3^2+1\right)\left(3^4+1\right)\ldots\left(3^{16}+1\right)\)
\(A=3^{32}-1\)
b) \(B=\left(4^2-1\right)\left(4^2+1\right)\left(4^4+1\right)\ldots\left(4^{64}+1\right)\)
\(B=4^{128}-1\)
c) \(\Leftrightarrow C=\left(5^2-1\right)\left(5^2+1\right)\left(5^4+1\right)\left(5^8+1\right)\ldots\left(5^{128}+1\right)+\left(5^{256}-1\right)\)
\(C=5^{256}-1+5^{256}-1=2\cdot5^{256}-2\)
a: \(A=8\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)
\(=\left(3^2-1\right)\left(3^2+1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)
\(=\left(3^4-1\right)\left(3^4+1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)
\(=\left(3^8-1\right)\left(3^8+1\right)\left(3^{16}+1\right)\)
\(=\left(3^{16}-1\right)\left(3^{16}+1\right)\)
\(=3^{32}-1\)
b: \(B=15\left(4^2+1\right)\left(4^4+1\right)\cdot\ldots\cdot\left(4^{64}+1\right)\)
\(=\left(4^2-1\right)\left(4^2+1\right)\left(4^4+1\right)\cdot\ldots\cdot\left(4^{64}+1\right)\)
\(=\left(4^4-1\right)\left(4^4+1\right)\cdot\left(4^8+1\right)\cdot\left(4^{16}+1\right)\cdot\left(4^{32}+1\right)\cdot\left(4^{64}+1\right)\)
\(=\left(4^8-1\right)\cdot\left(4^8+1\right)\cdot\left(4^{16}+1\right)\cdot\left(4^{32}+1\right)\cdot\left(4^{64}+1\right)\)
\(=\left(4^{16}-1\right)\cdot\left(4^{16}+1\right)\cdot\left(4^{32}+1\right)\cdot\left(4^{64}+1\right)\)
\(=\left(4^{32}-1\right)\cdot\left(4^{32}+1\right)\cdot\left(4^{64}+1\right)\)
\(=\left(4^{64}-1\right)\cdot\left(4^{64}+1\right)=4^{128}-1\)
c: \(C=24\left(5^2+1\right)\left(5^4+1\right)\cdot\ldots\cdot\left(5^{128}+1\right)+\left(5^{256}-1\right)\)
\(=\left(5^2-1\right)\left(5^2+1\right)\left(5^4+1\right)\cdot\ldots\cdot\left(5^{128}+1\right)+\left(5^{256}-1\right)\)
\(=\left(5^4-1\right)\left(5^4+1\right)\left(5^8+1\right)\cdot\ldots\cdot\left(5^{128}+1\right)+\left(5^{256}-1\right)\)
\(=\left(5^8-1\right)\left(5^8+1\right)\left(5^{16}+1\right)\cdot\left(5^{32}+1\right)\left(5^{64}+1\right)\cdot\left(5^{128}+1\right)+\left(5^{256}-1\right)\)
\(=\left(5^{16}-1\right)\left(5^{16}+1\right)\cdot\left(5^{32}+1\right)\left(5^{64}+1\right)\cdot\left(5^{128}+1\right)+\left(5^{256}-1\right)\)
\(=\left(5^{32}-1\right)\left(5^{32}+1\right)\left(5^{64}+1\right)\cdot\left(5^{128}+1\right)+\left(5^{256}-1\right)\)
\(=\left(5^{64}-1\right)\left(5^{64}+1\right)\cdot\left(5^{128}+1\right)+\left(5^{256}-1\right)\)
\(=\left(5^{128}-1\right)\cdot\left(5^{128}+1\right)+\left(5^{256}-1\right)\)
\(=5^{256}-1+5^{256}-1=2\cdot5^{256}-2\)