1) hai mu2+2 mu3 +2mu10 .......+2mu100
2) tim chu so tan cungcua so[2mu 2013]o tren co mu 2
hai so co BCNN la 2 mu 3.3.5mu 3 Biet mot trong hai so bang 2mu 2. 3.5,tim so con lai .
sao ko co ai tra loi vay
Cho Phép bằng 2+2 mu2+mu3+2mu4+2mu5+2mu6+2mu7+2mu8+2mu9+2mu10.Chung minh P chia hết cho 3
Lam on giúp mik voi
P =2+2^2+2^3+2^4+2^5+2^6+2^7+2^8+2^9+2^10
= ( 2+2^2 ) + ( 2^3 + 2^4 ) + ( 2^5 + 2^6 ) + ( 2^7 + 2^8 ) + ( 2^9 + 2^10 )
= 2.( 1+2 ) + 2^3.( 1+2 ) + 2^5.( 1+2 ) + 2^7.( 1+2 ) + 2^9.( 1 + 2 )
= 2.3+2^3.3+2^5.3+2^7.3+2^9.3
= ( 2+2^3+2^5+2^7+2^9).3 chia hết cho 3
=> P chia hết cho 3
tim stn n de B=n mu3 -2n mu 2+3/n-2 co gia tri la so tu nhien
tim so co 4 chu so abca sao cho (5*x+1) MU2
cau 1 ;2 so co tong la 346 biet so be la so co hai chu so va khi viet them chu so 3 vao truoc so be thi duoc so lon tim so be
cau 2 ; tong 2 so la 390 so be l¸o co 2 chu so va neu viet them chu so 3 vao truoc so be thi duoc so lon tim so lon
cau3;chu vi 1 khu dat hinh chu nhat =68 chieu dai hon chieu rong16m nguoi ta trong rau tren khu dat do TB cu 2m vuong trong duoc 2 kg rau tinh so rau o khu dat do
cau4 ; TBCcua 2 so la so nho nhat co 3chu so khac nhau biet so lon lon hon TBCcua 2so la 24 don vi tim so be va so lon
chung to rang B = 1/2mu 2 cong 1/3 mu 2 cong 1/4 mu 2 cong 1/5 mu 2 cong 1/6 mu 2cong 1/7 mu 2 cong 1/8 mu2 nho hon 1
tong cua mot so co 3 chu so va 1 so co 2 chu so la mot chu so co 4 chu so. biet hai so hang va tong khong thay doi gia tri khi ta doc so do tu trai qua phai hoac tu phai qua trai. tim so co 3 chu so tren !
tim so tu nhien x va chu so a de: 1+2+3+....+x=aa
o tren dau 2 chu so aa co dau nay nhe ! "-"
c/m 1/2mu 3 +1/3 mu 3 +..................+1/ 2006 mu 3<1/4
c/m 1/2 mu 3 +1/3 mu 3 +..................+1/2006 mu3 >1/15