giải pt:4(5x-3)-3(2x+1)=9
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\(4\left(5x-3\right)-3\left(2x+1\right)=9\)
\(\Leftrightarrow20x-12-6x-3=9\)
\(\Leftrightarrow14x=9+12+3\)
\(\Leftrightarrow14x=24\)
\(\Leftrightarrow x=\dfrac{24}{14}=\dfrac{12}{7}\)
Vậy tập nghiệm của PT là \(S=\left\{\dfrac{12}{7}\right\}\)
\(4\left(5x-3\right)-3\left(2x+1\right)=9\)
\(\Leftrightarrow20x-12-6x-3-9=0\)
\(\Leftrightarrow14x-24=0\)
\(\Leftrightarrow x=\dfrac{24}{14}\)
Vậy \(S=\left\{\dfrac{24}{14}\right\}\)
c: =>(x+2)(x+3)(x-5)(x-6)=180
=>(x^2-3x-10)(x^2-3x-18)=180
=>(x^2-3x)^2-28(x^2-3x)=0
=>x(x-3)(x-7)(x+4)=0
=>\(x\in\left\{0;3;7;-4\right\}\)
c: =>(x-3)(x+2)(2x+1)(3x-1)=0
=>\(x\in\left\{3;-2;-\dfrac{1}{2};\dfrac{1}{3}\right\}\)
a: ĐKXĐ: x<>-2/3
\(\frac{2x+1}{3x+2}=5\)
=>5(3x+2)=2x+1
=>15x+10=2x+1
=>13x=-9
=>\(x=-\frac{9}{13}\) (nhận)
b: ĐKXĐ: x∉{1;3}
\(\frac{2x^2-5x+2}{x-1}=\frac{2x^2+x+15}{x-3}\)
=>\(\left(2x^2-5x+2\right)\left(x-3\right)=\left(2x^2+x+15\right)\left(x-1\right)\)
=>\(2x^3-6x^2-5x^2+15x+2x-6=2x^3-2x^2+x^2-x+15x-15\)
=>\(-11x^2+17x-6=-x^2+14x-15\)
=>\(-10x^2+3x+9=0\)
=>\(10x^2-3x-9=0\)
=>\(x^2-\frac{3}{10}x-\frac{9}{10}=0\)
=>\(x^2-2\cdot x\cdot\frac{3}{20}+\frac{9}{400}-\frac{9}{400}-\frac{9}{10}=0\)
=>\(\left(x-\frac{3}{20}\right)^2=\frac{9}{400}+\frac{9}{10}=\frac{9}{400}+\frac{360}{400}=\frac{369}{400}\)
=>\(x-\frac{3}{20}=\pm\frac{3\sqrt{41}}{20}\)
=>\(\left[\begin{array}{l}x=\frac{3\sqrt{41}+3}{20}\left(nhận\right)\\ x=\frac{-3\sqrt{41}+3}{20}\left(nhận\right)\end{array}\right.\)
c: ĐKXĐ: x∉{3;-3}
\(\frac{2x+3}{x-3}-\frac{4}{x+3}=\frac{24}{x^2-9}+2\)
=>\(\frac{\left(2x+3\right)\left(x+3\right)-4\left(x-3\right)}{\left(x-3\right)\left(x+3\right)}=\frac{24+2\left(x^2-9\right)}{\left(x-3\right)\left(x+3\right)}\)
=>(2x+3)(x+3)-4(x-3)=\(24+2x^2-18\)
=>\(2x^2+6x+3x+9-4x+12=2x^2+6\)
=>5x+21=6
=>5x=-15
=>x=-3(loại)
\(ĐKXĐ:x\ge\frac{1}{2}\)
Phương trình đã cho tương đương :
\(4.\left(x^2+1\right)+3.x.\left(x-2\right).\sqrt{2x-1}=2x^3+10x\)
\(\Leftrightarrow3x\left(x-2\right)\sqrt{2x-1}=2x^3-8x^2+10x-4\)
\(\Leftrightarrow3x.\left(x-2\right).\sqrt{2x-1}=2.\left(x-2\right).\left(x-1\right)^2\) (1)
Dễ thấy \(x=2\) là một nghiệm của (1). Xét \(x\ne2\). Khi đó ta có :
\(3x.\sqrt{2x-1}=2.\left(x-1\right)^2\)(*)
Đặt \(\sqrt{2x-1}=a\left(a\ge0\right)\Rightarrow-a^2=1-2x\)
Khi đó pt (*) có dạng :
\(3x.a=2.\left(x^2-a^2\right)\)
\(\Leftrightarrow2x^2-3xa-2a^2=0\)
\(\Leftrightarrow2x^2-4ax+xa-2a^2=0\)
\(\Leftrightarrow2x.\left(x-2a\right)+a.\left(x-2a\right)=0\)
\(\Leftrightarrow\left(x-2a\right)\left(a+2x\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}2a=x\\a=-2x\end{cases}}\)
+) Với \(2a=x\Rightarrow2\sqrt{2x-1}=x\left(x\ge0\right)\)
\(\Leftrightarrow x^2=4.\left(2x-1\right)\)
\(\Leftrightarrow x^2-8x+4=0\)
\(\Leftrightarrow x=4\pm2\sqrt{3}\) ( Thỏa mãn )
+) Với \(a=-2x\Rightarrow\sqrt{2x-1}=-2x\left(x\le0\right)\)
\(\Leftrightarrow4x^2=2x-1\)
\(\Leftrightarrow4x^2-2x+1=0\) ( Vô nghiệm )
Vậy phương trình đã cho có tập nghiệm \(S=\left\{4\pm2\sqrt{3},2\right\}\)
a, ĐK: \(\left(x+1\right)\left(x^2+2x-1\right)\ge0\)
\(x^2+5x+2=4\sqrt{x^3+3x^2+x-1}\)
\(\Leftrightarrow x^2+2x-1+3\left(x+1\right)-4\sqrt{\left(x+1\right)\left(x^2+2x-1\right)}=0\)
TH1: \(x\ge-1\)
\(pt\Leftrightarrow\left(\sqrt{x^2+2x-1}-\sqrt{x+1}\right)\left(\sqrt{x^2+2x-1}-3\sqrt{x+1}\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}\sqrt{x^2+2x-1}=\sqrt{x+1}\\\sqrt{x^2+2x-1}=3\sqrt{x+1}\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2+2x-1=x+1\\x^2+2x-1=9x+9\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2+x-2=0\\x^2-7x-10=0\end{matrix}\right.\)
\(\Leftrightarrow...\)
TH2: \(x< -1\)
\(pt\Leftrightarrow\left(\sqrt{-x^2-2x+1}-\sqrt{-x-1}\right)\left(\sqrt{-x^2-2x+1}-3\sqrt{-x-1}\right)=0\)
\(\Leftrightarrow...\)
Bài này dài nên ... cho nhanh nha, đoạn sau dễ rồi
\(5x-4\left(6x+18-x^2-3x\right)=\left(12-8x-6x+4x^2\right)+2\)
\(\Leftrightarrow5x-4\left(-x^2+3x+18\right)=\left(4x^2-14x+12\right)+2\)
\(\Leftrightarrow4x^2-7x-72=4x^2-14x+14\Leftrightarrow7x=86\Leftrightarrow x=\dfrac{86}{7}\)
a) Sửa đề: \(\dfrac{3}{5x-1}+\dfrac{2}{3-x}=\dfrac{4}{\left(1-5x\right)\left(x-3\right)}\)
ĐKXĐ: \(x\notin\left\{3;\dfrac{1}{5}\right\}\)
Ta có: \(\dfrac{3}{5x-1}+\dfrac{2}{3-x}=\dfrac{4}{\left(1-5x\right)\left(x-3\right)}\)
\(\Leftrightarrow\dfrac{3\left(3-x\right)}{\left(5x-1\right)\left(3-x\right)}+\dfrac{2\left(5x-1\right)}{\left(3-x\right)\left(5x-1\right)}=\dfrac{4}{\left(5x-1\right)\left(3-x\right)}\)
Suy ra: \(9-3x+10x-2=4\)
\(\Leftrightarrow7x+7=4\)
\(\Leftrightarrow7x=-3\)
hay \(x=-\dfrac{3}{7}\)
Vậy: \(S=\left\{-\dfrac{3}{7}\right\}\)
\(4\left(5x-3\right)-3\left(2x+1\right)=9\)
\(\Leftrightarrow20x-12-6x-3=9\)
\(\Leftrightarrow14x-15=9\)
\(\Leftrightarrow14x=24\)
\(\Leftrightarrow x=\dfrac{12}{7}\)
Vậy phương trình có nghiệm là: \(x=\dfrac{12}{7}\)
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