12+22+........+102
=1.(2-1)+2.(3-1)+..........+10.(11-1)
=1.2-1+2.3-2+......+10.11-10
=(1.2+2.3+......+10.11)-(1+2+.........+10)
Bạn tự là tiếp nha
1^2+2^2+3^2+.....+10^2
= 1 + 4 + 9 + 16 + 25 + 36 + 49 + 64 + 81 + 100
= 385
12+22+........+102
=1.(2-1)+2.(3-1)+..........+10.(11-1)
=1.2-1+2.3-2+......+10.11-10
=(1.2+2.3+......+10.11)-(1+2+.........+10)
Bạn tự là tiếp nha
1^2+2^2+3^2+.....+10^2
= 1 + 4 + 9 + 16 + 25 + 36 + 49 + 64 + 81 + 100
= 385
cac ban giup minh nhe:
1+2+2^2+...+2^2008/1-2^2008
cam on cac ban da giup minh
tim x biet:
10-2(x+3)=5(x-2)
3x+3x+1+3x+2=351
cac ban giup minh voi nhe
nho phai co cach la day
tim x biet:
10-2(x+3)=5(x-2)
3x+3x+1+3x+2=351
cac ban giup minh voi nhe
nho phai co cach la day
tim x biet:
10-2(x+3)=5(x-2)
3x+3x+1+3x+2=351
cac ban giup minh voi nhe
nho phai co cach la day
\(y=\frac{1}{2^2}+\frac{1}{3^2}+...+\frac{1}{2013^2}\)
giup minh nhe may ban
thuc hien phep tinh a) 4.52- 81 : 32 ( cac ban giup minh nhe)
2^3+3^3+4^3+...+20^3=? Giup minh giai bai nay nhe giai thich cach lam nhe cac ban
cho a =1/2^2 +1/2^3 +1/2^4+.....+1/2^100 c/m A khong phai la so tu nhien
CAC BAN GIUP MINH GIAI NHE! AI GIAI DUNG MINH TICH CHO
so sanh (a+1).(a+2).(a+3)-a.(a+1).(a+2) va 3(a+1).(a+2)
b,tinh
M=1.2+2.3+3.4+...+ 2002.2003
GIUP MINH NHANH LEN NHE CAC BAN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!