Tìm x:
\(\frac{1}{2}\left(6x-5\right)-5x=1\frac{3}{5}\)
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\(\frac{3x-1}{2}-\frac{2-6x}{5}=\frac{1}{2}+\left(3x-1\right)\)
\(\Leftrightarrow\frac{3x-1}{2}+\frac{2\left(3x-1\right)}{5}-\left(3x-1\right)=\frac{1}{2}\)
\(\Leftrightarrow\left(3x-1\right)\left(\frac{1}{2}+\frac{2}{5}-1\right)=\frac{1}{2}\)
\(\Leftrightarrow\frac{-1}{10}\left(3x-1\right)=\frac{1}{2}\)
\(\Leftrightarrow3x-1=-5\)
\(\Leftrightarrow3x=-4\Leftrightarrow x=\frac{-4}{3}\)
Vậy nghiệm duy nhất của phương trình là\(x=\frac{-4}{3}\)
\(\left(x^2+2x+1\right)-\frac{x+1}{3}=\frac{6\left(x+1\right)^2-5x-5}{6}\)
\(\Leftrightarrow\left(x+1\right)^2-\frac{x+1}{3}=\frac{6\left(x+1\right)^2-5\left(x+1\right)}{6}\)
\(\Leftrightarrow\left(x+1\right)^2-\frac{x+1}{3}=\frac{\left(x+1\right)\left(6x+6-5\right)}{6}\)
\(\Leftrightarrow\left(x+1\right)^2-\frac{x+1}{3}=\frac{\left(x+1\right)\left(6x+1\right)}{6}\)
\(\Leftrightarrow\left(x+1\right)^2-\frac{x+1}{3}-\frac{\left(x+1\right)\left(6x+1\right)}{6}=0\)
\(\Leftrightarrow\left(x+1\right)\left(x+1-\frac{1}{3}-\frac{6x+1}{6}\right)=0\)
\(\Leftrightarrow\frac{1}{2}\left(x+1\right)=0\)
\(\Leftrightarrow x+1=0\Leftrightarrow x=-1\)
Vậy nghiệm duy nhất của phương trình là\(x=-1\)
\(lim\dfrac{x^5-5x^3+2x^2+6x-4}{x^3-x^2-x+1}\)
\(=lim\dfrac{1-\dfrac{5}{x^2}+\dfrac{2}{x^3}+\dfrac{6}{x^4}-\dfrac{4}{x^5}}{\dfrac{1}{x^2}-\dfrac{1}{x^3}-\dfrac{1}{x^4}+\dfrac{1}{x^5}}\)
\(=\dfrac{1}{0}=+\infty\)
\(\left\{{}\begin{matrix}lim\left(1-\dfrac{5}{x^2}+\dfrac{2}{x^3}+\dfrac{6}{x^4}-\dfrac{4}{x^5}\right)=1>0\\lim\left(\dfrac{1}{x^2}-\dfrac{1}{x^3}-\dfrac{1}{x^4}+\dfrac{1}{x^5}\right)=0\end{matrix}\right.\)
Suy ra:\(lim\dfrac{x^5-5x^3+2x^2+6x-4}{x^3-x^2-x+1}=lim\dfrac{1-\dfrac{5}{x^2}+\dfrac{2}{x^3}+\dfrac{6}{x^4}-\dfrac{4}{x^5}}{\dfrac{1}{x^2}-\dfrac{1}{x^3}-\dfrac{1}{x^4}+\dfrac{1}{x^5}}=+\infty\)
\(a.ĐKXĐ:\hept{\begin{cases}1-3x\ne0\\3x+1\ne0\\x\ge0\end{cases}\Leftrightarrow\hept{\begin{cases}x=\frac{1}{3}\\...\\x\ge0\end{cases}}}\)
\(b,M=\left(\frac{3x}{1-3x}+\frac{2x}{3x+1}\right):\frac{6x^2+10}{1-6x+9x^2}\)
\(=\left(\frac{3x\left(1+3x\right)}{\left(1-3x\right)\left(1+3x\right)}+\frac{2x\left(1-3x\right)}{\left(1-3x\right)\left(1+3x\right)}\right).\frac{\left(1-3x\right)^2}{6x^2+10}\)
\(=\left(\frac{3x+9x^2+2x-6x^2}{\left(1-3x\right)\left(1+3x\right)}\right).\frac{\left(1-3x\right)^2}{6x^2+10}\)
\(=\frac{5x+3x^2}{1+3x}.\frac{1-3x}{2\left(3x^2+5\right)}\)
==>Sai đề không mem
(x - 7)x+1 - (x - 7)x+1 = 0
<=> 0 = 0
Vậy phương trình có nghiệm với mọi x thuộc R
b/ Chi cần áp dụng tính chất dãy tỷ số bằng nhau thì ra thôi
a) <=> \(6x^2-5x+3-2x+3x\left(3-2x\right)=0\)
<=> \(6x^2-5x+3-2x+9x-6x^2=0\)
<=> \(2x+3=0\)
<=> \(x=\frac{-3}{2}\)
b) <=> \(10\left(x-4\right)-2\left(3+2x\right)=20x+4\left(1-x\right)\)
<=> \(10x-40-6-4x=20x+4-4x\)
<=> \(6x-46-16x-4=0\)
<=> \(-10x-50=0\)
<=> \(-10\left(x+5\right)=0\)
<=> \(x+5=0\)
<=> \(x=-5\)
c) <=> \(8x+3\left(3x-5\right)=18\left(2x-1\right)-14\)
<=> \(8x+9x-15=36x-18-14\)
<=> \(8x+9x-36x=+15-18-14\)
<=> \(-19x=-14\)
<=> \(x=\frac{14}{19}\)
d) <=>\(2\left(6x+5\right)-10x-3=8x+2\left(2x+1\right)\)
<=> \(12x+10-10x-3=8x+4x+2\)
<=> \(2x-7=12x+2\)
<=> \(2x-12x=7+2\)
<=> \(-10x=9\)
<=> \(x=\frac{-9}{10}\)
e) <=> \(x^2-16-6x+4=\left(x-4\right)^2\)
<=> \(x^2-6x-12-\left(x-4^2\right)=0\)
<=> \(x^2-6x-12-\left(x^2-8x+16\right)=0\)
<=> \(x^2-6x-12-x^2+8x-16=0\)
<=> \(2x-28=0\)
<=> \(2\left(x-14\right)=0\)
<=> x-14=0
<=> x=14
a) \(\left(\frac{x+2}{98}+1\right)+\left(\frac{x+3}{97}+1\right)=\left(\frac{x+4}{96}+1\right)+\left(\frac{x+5}{95}+1\right)\)
=> \(\frac{x+2+98}{98}+\frac{x+3+97}{97}=\frac{x+4+96}{96}+\frac{x+5+95}{95}\)
=> \(\frac{x+100}{98}+\frac{x+100}{97}=\frac{x+100}{96}+\frac{x+100}{95}\)
=> \(\frac{x+100}{98}+\frac{x+100}{97}-\frac{x+100}{96}-\frac{x+100}{95}=0\)
=> \(\left(x+100\right)\left(\frac{1}{98}+\frac{1}{97}-\frac{1}{96}-\frac{1}{95}\right)=0\)
Ta có : \(\frac{1}{98}+\frac{1}{97}\ne\frac{1}{96}+\frac{1}{95}\) => \(\frac{1}{98}+\frac{1}{97}-\frac{1}{96}-\frac{1}{95}\ne0\)
=> \(x+100=0\)
=> \(x=-100\)
Nhiều thế bạn tách từng câu ra mik giải cho (olm ko dc trừ điểm câu này của e)
Phần b bạn tự làm nhé, chỉ cần quy đồng lên lấy MC = 105 là được mà
Phần a mình giải ntn:
PT \(\Leftrightarrow\) \(\frac{x+100}{98}+\frac{x+100}{97}=\frac{x+100}{96}+\frac{x+100}{95}\)
\(\Leftrightarrow\)\(\left(x+100\right)\left(\frac{1}{98}+\frac{1}{97}-\frac{1}{96}-\frac{1}{95}\right)=0\)
\(\Leftrightarrow\)\(x+100=0\)
\(\Leftrightarrow x=-100\)
\(\frac{1}{2}\left(6x-5\right)-5x=1\frac{3}{5}\)
\(\Rightarrow6x.\frac{1}{2}-5.\frac{1}{2}-5x=\frac{8}{5}\)
\(\Rightarrow3x-\frac{5}{2}-5x=\frac{8}{5}\)
\(\Rightarrow3x-5x=\frac{8}{5}+\frac{5}{2}\)
\(\Rightarrow-2x=\frac{16}{10}+\frac{25}{10}\)
\(\Rightarrow-2x=\frac{41}{10}\)
\(\Rightarrow x=\frac{41}{10}:-2\)
\(\Rightarrow x=\frac{41}{10}.\frac{1}{-2}\)
\(\Rightarrow x=-\frac{41}{20}\)
Vậy \(x=-\frac{41}{20}\)
Chúc bạn học tốt !!!!