x^4 +2x^3 + 2x^2+4x +5 = 0
giải pt
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1:
a: =>(|x|+4)(|x|-1)=0
=>|x|-1=0
=>x=1; x=-1
b: =>x^2-4>=0
=>x>=2 hoặc x<=-2
d: =>|2x+5|=2x-5
=>x>=5/2 và (2x+5-2x+5)(2x+5+2x-5)=0
=>x=0(loại)
a: ĐKXĐ: x∈R
\(\frac{5}{x^2-2x+2}-\frac{8}{x^2-2x+5}=3\)
=>\(\frac{5\left(x^2-2x+5\right)-8\left(x^2-2x+2\right)}{\left(x^2-2x+2\right)\left(x^2-2x+5\right)}=3\)
=>\(3\left(x^2-2x+2\right)\left(x^2-2x+5\right)=5x^2-10x+25-8x^2+16x-16=-3x^2+6x+9\)
=>\(3\left\lbrack\left(x^2-2x\right)^2+7\left(x^2-2x\right)+10\right\rbrack=-3\left(x^2-2x\right)+9\)
=>\(\left(x^2-2x\right)^2+7\left(x^2-2x\right)+10=-\left(x^2-2x\right)+3\)
=>\(\left(x^2-2x\right)^2+8\left(x^2-2x\right)+7=0\)
=>\(\left(x^2-2x+1\right)\left(x^2-2x+7\right)=0\)
=>\(x^2-2x+1=0\)
=>\(\left(x-1\right)^2=0\)
=>x-1=0
=>x=1(nhận)
b: ĐKXĐ: x<>0
\(\frac{x^2-4x+3}{2x}+\frac{x^2+12x+3}{x^2+3}=4\)
=>\(\frac{x^2+3}{2x}-2+\frac{12x}{x^2+3}+1=4\)
=>\(\frac{x^2+3}{2x}+\frac{12x}{x^2+3}=4+2-1=6-1=5\)
=>\(\frac{\left(x^2+3\right)^2+24x^2}{2x\left(x^2+3\right)}=5\)
=>\(\left(x^2+3\right)^2+24x^2-10x\left(x^2+3\right)=0\)
=>\(\left(x^2+3\right)^2-4x\left(x^2+3\right)-6x\left(x^2+3\right)+24x^2=0\)
=>\(\left(x^2+3\right)\left(x^2+3-4x\right)-6x\left(x^2+3-4x\right)=0\)
=>\(\left(x^2-6x+3\right)\left(x^2-4x+3\right)=0\)
TH1: \(x^2-6x+3=0\)
=>\(x^2-6x+9-6=0\)
=>\(\left(x-3\right)^2=6\)
=>\(\left[\begin{array}{l}x-3=\sqrt6\\ x-3=-\sqrt6\end{array}\right.\Rightarrow\left[\begin{array}{l}x=\sqrt6+3\left(nhận\right)\\ x=-\sqrt6+3\left(nhận\right)\end{array}\right.\)
TH2: \(x^2-4x+3=0\)
=>\(x^2-x-3x+3=0\)
=>(x-1)(x-3)=0
=>x=1(nhận) hoặc x=3(nhận)
\(a, x(x+3)-(2x-1)(x+3)=0\)
\(⇔(x+3)(1-x)=0\)
\(⇔\left[\begin{array}{} x+3=0\\ 1-x=0 \end{array}\right.\)
\(⇔\left[\begin{array}{} x=-3\\ x=1 \end{array}\right.\)
Vậy phương trình có tập nghiệm là S={\(-3; 1\)}
\(b, 3x-5(x+2)=3(4-2x)\)
\(⇔3x-5x-10=12-6x\)
\(⇔3x-5x+6x=12+10\)
\(⇔4x=22\)
\(⇔x=\dfrac{22}{4}\)
Vậy pt có 1 nghiệm là \(x=\dfrac{22}{4}\)
\(c, (4x-3)(5x-6)=(4x-3)(2x-3)\)
\(⇔5x-6=2x-3\)
\(⇔5x-2x=-3+6\)
\(⇔3x=3\)
\(⇔x=1\)
Vậy pt có 1 nghiệm là \(x=1\)
\(\frac{5}{3}-\left(2x-\frac{2}{4}\right)\ge x-\left(4x-\frac{3}{6}\right)\)
\(\Leftrightarrow\frac{5}{3}-2x+\frac{1}{2}\ge x-4x+\frac{1}{2}\)
\(\Leftrightarrow x\ge-\frac{5}{3}\)
Ý c cx vậy nha ! Chuyển vế rồi thu gọn lại
a) \(\left\{{}\begin{matrix}2x+3y=5\\4x-5y=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}4x+6y=10\\4x-5y=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x+3y=5\\11y=9\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x+3\cdot\dfrac{9}{11}=5\\y=\dfrac{9}{11}\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x+\dfrac{27}{11}=5\\y=\dfrac{9}{11}\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x=\dfrac{28}{11}\\y=\dfrac{9}{11}\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{14}{11}\\y=\dfrac{9}{11}\end{matrix}\right.\)
Vậy: \(x=\dfrac{14}{11};y=\dfrac{9}{11}\)