Mọi người ơi, giúp mình với:
\(\left(x+3\right)^{2014}=\left(x+3\right)^{2012}\)
\(\left(x-3\right)^{2014}=\left(x-3\right)^{2011}\)
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`(x+3)^2014 = (x+3)^2012`
`(x+3)^2014 -(x+3)^2012 =0`
`(x+3)^2012 [(x+3)^2 -1]=0`
TH1 :`(x+3)^2012 =0 => x+3 =0 => x=-3`
TH2 :`(x+3)^2 -1 =0 => (x+3)^2 =1 => [(x+3=1),(x+3=-1):}`
`=> [(x=-2),(x=-4):}`
`(x+3)^2014 = (x+3)^2012`
`=> (x+3)^2014 - (x+3)^2012 = 0`
`=> (x+3)^2 * (x+3)^2012 - (x+3)^2012 = 0`
`=> (x+3)^2012 * [ (x+3)^2 - 1] =0`
`=>`\(\left[{}\begin{matrix}\left(x+3\right)^{2012}=0\\\left(x+3\right)^2-1=0\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}x+3=0\\\left(x+3\right)^2=1\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}x=-3\\x+3=1\\x+3=-1\end{matrix}\right.\)
`=>`\(\left[{}\begin{matrix}x=-3\\x=-2\\x=-4\end{matrix}\right.\)
Vậy, `x = {-3; -2; -4}.`
1/
\(1+\frac{2014}{2}+...+\frac{4024}{2012}=1+\left(1+\frac{2012}{2}\right)+\left(1+\frac{2013}{3}\right)+...+\left(1+\frac{2012}{2012}\right)\)
\(=2012+2012\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2012}\right)=2012\left(1+\frac{1}{2}+...+\frac{1}{2012}\right)\)
Phương trình đã cho tương đương:
\(\left(1+\frac{1}{2}+...+\frac{1}{2012}\right).503x=2012\left(1+\frac{1}{2}+...+\frac{1}{2012}\right)\)
\(\Leftrightarrow503x=2012\)
\(\Leftrightarrow x=4\)
2/
\(\frac{8}{1.9}+\frac{8}{9.17}+...+\frac{8}{49.57}+\frac{58}{57}+2x-2=2x+\frac{7}{3}+5x-\frac{8}{4}\)
\(\Leftrightarrow\frac{1}{1}-\frac{1}{9}+\frac{1}{9}-\frac{1}{17}+...+\frac{1}{49}-\frac{1}{57}+\left(1+\frac{1}{57}\right)-2-\frac{7}{3}+\frac{8}{4}=5x\)
\(\Leftrightarrow\)\(5x=\frac{17}{3}\Leftrightarrow x=\frac{17}{15}\)
3/
Ta có: \(1+\frac{1}{n\left(n+2\right)}=\frac{n\left(n+2\right)+1}{n\left(n+2\right)}=\frac{\left(n+1\right)^2}{n\left(n+2\right)}\)
\(\left(1+\frac{1}{1.3}\right).\left(1+\frac{1}{2.4}\right).....\left(1+\frac{1}{n\left(n+2\right)}\right)\)\(=\frac{2^2}{1.3}.\frac{3^2}{2.4}.\frac{4^2}{3.5}.\frac{5^2}{4.6}.......\frac{\left(n+1\right)^2}{n\left(n+2\right)}\)
\(=2.\frac{n+1}{n+2}
a) Ta có:
\(\frac{x+11}{12}+\frac{x+11}{13}+\frac{x+11}{14}=\frac{x+11}{15}+\frac{x+11}{16}\)
\(\Rightarrow\left(x+11\right)\left(\frac{1}{12}+\frac{1}{13}+\frac{1}{14}\right)=\left(x+11\right)\left(\frac{1}{15}+\frac{1}{16}\right)\)
Mà ta có:
\(\frac{1}{12}+\frac{1}{13}+\frac{1}{14}\ne\frac{1}{15}+\frac{1}{16}\)
\(\Rightarrow x+11=0\Rightarrow x=-11\)
Ta có:
\(A=1+x+x^2+x^3+...+x^{100}\)
Đặt \(B=x+x^2+x^3+...+x^{100}\)
\(\Rightarrow B=\left(-11\right)+\left(-11\right)^2+\left(-11\right)^3+...+\left(-11\right)^{100}\)
\(\Rightarrow-11B=\left(-11\right)^2+\left(-11\right)^3+\left(-11\right)^4+...+\left(-11\right)^{101}\)
\(\Rightarrow-11B-B=\left(-11\right)^{101}-\left(-11\right)\)
\(\Rightarrow-12B=\left(-11\right)^{101}+11\Rightarrow B=\frac{\left(-11\right)^{101}+11}{-12}\)
\(\Rightarrow A=1+B=\frac{\left(-11\right)^{101}+11}{-12}+1\)
x=100
nên x+1=101
\(f\left(x\right)=x^{2014}-\left(x+1\right)\left(x^{2013}-x^{2012}+...-x^2+x\right)+25\)
\(=x+25\)
=x+25=100+25=125
\(a)2018=\left|x-2016\right|+\left|x-2014\right|\)
\(\Rightarrow\hept{\begin{cases}x-2016+x-2014=2018\\x-2016+x-2014=-2018\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}2x-2016-2014=2018\\2x-2016-2014=-2018\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}2x=2018+2016+2014\\2x=-2018+2016+2014\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}2x=6048\\2x=2012\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x=3024\\x=1006\end{cases}}\)
vậy x = 3024 hoặc x = 1006
b) \(\left(x-3\right)^x-\left(x-3\right)^{x+2}=0\)
\(\Rightarrow\left(x-3\right)^x-\left(x-3\right)^x\left(x-3\right)^2=0\)
\(\Rightarrow\left(x-3\right)^x\left[1-\left(x-3\right)^2\right]=0\)
\(\Rightarrow\hept{\begin{cases}\left(x-3\right)^x=0\\1-\left(x-3\right)^2=0\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x-3=0\\\left(x-3\right)^2=1\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x=3\\\left(x-3\right)^2=1\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x=3\\x-3=1\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x=3\\x=4\end{cases}}\)
vậy x = 3 hoặc x = 4
\(f\left(x\right)=x^3-3x^2+3x+3=\left(x-1\right)^3+2\)
Thay vào là OK!!
\(\left(x+3\right)^{2014}=\left(x+3\right)^{2012}\Leftrightarrow\left(x+3\right)^{2014}-\left(x+3\right)^{2012}=0\)
\(\Leftrightarrow\left(x+3\right)^{2012}\left[\left(x+3\right)^2-1\right]=0\)
TH1 : \(x=-3\)
TH2 : \(\left(x+3-1\right)\left(x+3+1\right)=0\Leftrightarrow\left(x+2\right)\left(x+4\right)=0\Leftrightarrow x=-2;-4\)
\(\left(x-3\right)^{2014}=\left(x-3\right)^{2011}\Leftrightarrow\left(x-3\right)^{2014}-\left(x-3\right)^{2011}=0\)
\(\Leftrightarrow\left(x-3\right)^{2011}\left[\left(x-3\right)^3-1\right]=0\)
TH1 : \(x=3\)
TH2 : \(\left(x-4\right)\left(x^2+4x+16\ne0\right)=0\Leftrightarrow x=4\)