10^2+11^2+12^2 và 13^2+14^2
tìm x sao cho x+2/10^10+x+2/11^11+x+2/12^12=x+2/13^13+x+2/14^14
So sánh : 10^2 + 11^2 + 12^2 + và 13^2 + 14^2
a) \(4^{13}+4^{14}+4^{15}+4^{16}=4^{13}\left(1+4\right)+4^{14}\left(1+4\right)=4^{13}.5+4^{14}.5=5\left(4^{13}+4^{14}\right)⋮5\Rightarrow dpcm\)
c) \(2^{10}+2^{11}+2^{12}+2^{13}+2^{14}+2^{15}\)
\(=2^{10}\left(1+2+2^2\right)+2^{13}\left(1+2+2^2\right)\)
\(=2^{10}.7+2^{13}.7=7\left(2^{10}+2^{13}\right)⋮7\Rightarrow dpcm\)
Câu c bạn xem lại đê
1/2+2/3+3/4+4/5+5/6+6/7+7/8+8/9+9/10+10/11+11/12+12/13+13/14+14/15=?
\(\dfrac{10^2+11^2+12^2}{13^2+14^2}\)
Lời giải:
\(\frac{10^2+11^2+12^2}{13^2+14^2}=\frac{365}{365}=1\)
(-2/11+ 3/12 +-4/13 +5/14) : (-4/11 + 6/12+ -8/13 +10/14)
(-2/11+ 3/12 +-4/13 +5/14) : (-4/11 + 6/12+ -8/13 +10/14)0000000000000000000000000000000000000= 0
(10^2+11^2+12^2):(13^2+14^2)
10^2+11^2+12^2/13^2+14^2
(10^2+11^2+12^2):(13^2+14^2)