Chứng minh 3^2014+3^2013-3^2012
cho A=1*4/2*3 + 2*5/3*4+3*6/4*5+.....+2013*2016/2014*2015 . Chứng minh 2012< A < 2013
Chứng minh rằng : 32014 +32013 -32012 chia het cho 11
Ta có :
\(3^{2014}+3^{2013}-3^{2012}\)
\(=3^{2012}\left(3^2+3-1\right)\)
\(=3^{2012}.11\)
\(\Rightarrow3^{2014}+3^{2013}-3^{2012}\)
\(\RightarrowĐPCM\)
chứng minh rằng: 32014 - 32013 + 32012 chia hết cho 63
\(3^{2014}-3^{2013}+3^{2012}=3^{2012}\left(9-3+1\right)\)
\(=3^{2012}\cdot7=3^{2010}\cdot63⋮63\)
Dpcm
32014 - 32013 + 32012
= 32012 x 32 - 32012 x 3 + 32012 x 1
= 32012 x 9 - 32012 x 3 + 32012 x 1
= 32012 x (9 - 3 + 1)
= 32012 x 7
= 32010 x 32 x 7
= 32010 x 9 x 7
= 32010 x 63
Mà 63 \(⋮\) 63 nên 32010 x 63 \(⋮\) 63 => 32014 - 32013 + 32012 \(⋮\)63
(1/2012+1/2013-1/2014)/(5/2012+5/2013-5/2014)-(2/2103+2/2014-2/2015)/(3/2013+3/2014-3/2015)
\(\frac{\frac{1}{2012}+\frac{1}{2013}-\frac{1}{2014}}{\frac{5}{2012}+\frac{5}{2013}-\frac{5}{2014}}-\frac{\frac{2}{2013}+\frac{2}{2014}-\frac{2}{2015}}{\frac{3}{2013}+\frac{3}{2014}-\frac{3}{2015}}\)
=\(\frac{\frac{1}{2012}+\frac{1}{2013}-\frac{1}{2014}}{5\left(\frac{1}{2012}+\frac{1}{2013}-\frac{1}{2014}\right)}-\frac{2\left(\frac{1}{2013}+\frac{1}{2014}-\frac{1}{2015}\right)}{3\left(\frac{1}{2013}+\frac{1}{2014}-\frac{1}{2015}\right)}=\frac{1}{5}-\frac{2}{3}=\frac{3}{15}-\frac{10}{15}=-\frac{7}{15}\)
CHỨNG MINH 1/2-1/3+1/4-1/5+1/6-1/7+....+1/2012-1/2013+1/2014 < 2/5
chứng minh : 1/2 - 1/3 + 1/4 - 1/5 + 1/6 - 1/7+.............+ 1/2012 - 1/2013 + 1/2014 < 2/5 giải hộ mik
Chứng minh S=1/2-1/3+1/4-1/5+1/6-1/7+...+1/2012-1/2013+1/2014 <2/5
Tính hợp lý (2011/2012+2012/2013+2013/2014+2014/2015)×(1/5-2/3:10/3)
cho a,b khác 0 thỏa mãn a^2014 + b^2014 = a^2013 + b^2013 = a^2012 + b^2012
chứng minh rằng : a^2014 + b^2014 = a^2010 + b^2010
Đề \(\Rightarrow a^{2014}+b^{2014}-2\left(a^{2013}+b^{2013}\right)+a^{2012}+b^{2012}=0\)
\(\Leftrightarrow a^{2012}\left(a^2-2a+1\right)+b^{2012}\left(b^2-2b+1\right)=0\)
\(\Leftrightarrow a^{2012}\left(a-1\right)^2+b^{2012}\left(b-1\right)^2=0\)
\(\Leftrightarrow\left(a=0\text{ hoặc }a=1\right)\text{ và }\left(b=0\text{ hoặc }b=1\right)\)
\(+a=0\text{ hoặc }a=1\text{ thì }a^{2014}=a^{2010}\)
\(+b=0\text{ hoặc }b=1\text{ thì }b^{2014}=b^{2010}\)
Suy ra \(a^{2014}+b^{2014}=a^{2010}+b^{2010}\)