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\(\frac{400}{x}=\frac{100}{x}+\frac{300}{x}+10+\)\(1\)
<=> \(\frac{400-100-300}{x}=11\)
<=> \(\frac{0}{x}=11\)
Giải Phương Trình Sau:
\(\dfrac{x-342}{15}+\dfrac{x-323}{17}+\dfrac{x-300}{19}+\dfrac{x-273}{21}=10\)
Lời giải:
PT $\Leftrightarrow \frac{x-342}{15}-1+\frac{x-323}{17}-2+\frac{x-300}{19}-3+\frac{x-273}{21}-4=0$
$\Leftrightarrow \frac{x-357}{15}+\frac{x-357}{17}+\frac{x-357}{19}+\frac{x-357}{21}=0$
$(x-357)\left(\frac{1}{15}+\frac{1}{17}+\frac{1}{19}+\frac{1}{21}\right)=0$
Dễ thấy: $\frac{1}{15}+\frac{1}{17}+\frac{1}{19}+\frac{1}{21}\neq 0$
$\Rightarrow x-357=0$
$\Rightarrow x=357$
\(\left(x^2-x+1\right)+\left(x^2-2x+3\right)+...+\left(x^2-100x+199\right)=300\)
\(\Leftrightarrow100x^2-100x+\frac{\left[\left(199-1\right):2+1\right]\left(199+1\right)}{2}=300\)
\(\Leftrightarrow100x^2-100x+10000=300\)
\(\Leftrightarrow100x^2-100x+9700=0\)
\(\Leftrightarrow100\left(x^2-x+97\right)=0\)
\(\Leftrightarrow x^2-x+97=0\)
\(\Leftrightarrow x^2-2.x.\frac{1}{2}+\frac{1}{4}-\frac{1}{4}+97=0\)
\(\Leftrightarrow\left(x-\frac{1}{2}\right)^2+\frac{387}{4}=0\left(1\right)\)
Vì \(\left(x-\frac{1}{2}\right)^2\ge0;\forall x\)
\(\Rightarrow\left(x-\frac{1}{2}\right)^2+\frac{387}{4}\ge\frac{387}{4}>0;\forall x\)
\(\Rightarrow\)pt\(\left(1\right)\)vô nghiệm
Vậy pt trên vô nghiệm
a: \(\Leftrightarrow\left(\dfrac{x+2001}{5}+1\right)+\left(\dfrac{x+1999}{7}+1\right)+\left(\dfrac{x+1997}{9}+1\right)+\left(\dfrac{x+1995}{11}+1\right)=0\)
=>x+2006=0
=>x=-2006
b: \(\Leftrightarrow\left(\dfrac{x-15}{100}-1\right)+\left(\dfrac{x-10}{105}-1\right)+\left(\dfrac{x-100}{5}-1\right)=\left(\dfrac{x-100}{15}-1\right)+\left(\dfrac{x-105}{10}-1\right)+\left(\dfrac{x-110}{5}-1\right)\)
=>x-105=0
=>x=105
\(\dfrac{x-130}{20}\)+\(\dfrac{x-100}{25}\)+\(\dfrac{x-60}{30}\)+\(\dfrac{x-10}{35}\)=10
⇔\(\dfrac{2625\left(x-130\right)}{52500}\)+\(\dfrac{2100\left(x-100\right)}{52500}\)+\(\dfrac{1750\left(x-60\right)}{52500}\)+\(\dfrac{1500\left(x-10\right)}{52500}\)=\(\dfrac{525000}{52500}\)
⇔2625\(x\)-341250+2100\(x\)-210000+1750\(x\)-105000+1500\(x\)-15000=525000
⇔ 7975\(x\) = 1196250
⇔ \(x\) = \(\dfrac{1196250}{7975}\)
⇔\(x \) = 150
a: =>\(\dfrac{2x-4}{2014}+\dfrac{2x-2}{2016}< \dfrac{2x-1}{2017}+\dfrac{2x-3}{2015}\)
=>\(\dfrac{2x-2018}{2014}+\dfrac{2x-2018}{2016}< \dfrac{2x-2018}{2017}+\dfrac{2x-2018}{2015}\)
=>2x-2018<0
=>x<2019
b: \(\Leftrightarrow\left(\dfrac{3-x}{100}+\dfrac{4-x}{101}\right)>\dfrac{5-x}{102}+\dfrac{6-x}{103}\)
=>\(\dfrac{x-3}{100}+\dfrac{x-4}{101}-\dfrac{x-5}{102}-\dfrac{x-6}{103}< 0\)
=>\(x+97< 0\)
=>x<-97
400/x = 100/x + 300/x + 10 + 1
(=) 400/x = 100/x + 300/x + 10x/x + x/x = 0
(=) 400/x - 100/x - 300/x - 10x/x - x/x = 0
(=) (400 - 100 - 300 - 10x - x )/x = 0
(=) -11x/x = 0
(=) 11x/x = 0
=) 11x = 0
(=) x=0
x phải khác 0 thì mới thỏa măn ĐKXĐ của phương trình.
Vậy phương trình trên vô nghiệm