Tính tổng: 1/2+ 1/2^2+ 1/2^3+ 1/2^4+...+1/2^2004
Tính các tổng:
1/ S = 1 - 2 - 3 + 4 + 5 - 6 - 7 + 8 + ...+ 2001- 2002 - 2003 + 2004
2/ S = 1 + 2 - 3 - 4 + 5 + 6 - 7 - 8 + 9 + ...+ 2002 - 2003 - 2004 + 2005 + 2006
S=(1+2-3-4)+(5+6-7-8)+......+(2001+2002-2003-2004)+(2005+2006)
S=(-4)+(-4)+.......+(-4)+(2005+2006)
Dãy S có 2004-1:1+1=2004 số hạng
Dãy S có 2004:4=501 số -4
Do đó S=-4.501=-2004
S=-2004+(2005+2006)
S=-2004+4011
S=2007
1,S=(1-2-3+4)+(5-6-7+8)+.......+(2001-2002-2003+2004)
S=0+0+.........................+0
S=0
2,hình như pan gi sai đề
Bài 1 a)Tính tổng 12+22+32+...+n2
b)Tính tổng 13+23+33+...+n3
Bài 2 : CTR B = 1-\(\frac{1}{2^2}\)-\(\frac{1}{3^2}\)-...-\(\frac{1}{2004^2}\)>\(\frac{1}{2004}\)
Bài 3: CMR S=1/22-1/24+...+1/24n-2-1/24n+...+1/22002-1/22004<\(\frac{1}{5}\)
chứng minh rằng tổng S= 1- 1/22- 1/32- 1/42-...-1/20042> 1/2004
sao chị không hiểu em ghi cái gì hết
tính tổng: S=1^2-2^2+3^2-4^2+...+2003^2-2004^+2005^2-2006^2
lập phương trình bằng máy tính casio 500ms
ta có 12 - 22 = - 3
32 - 42 = - 7
.................
20052 - 20062 = -4011
-{(4011+3)[(4011-3):4+1]:2} = -2013021
1/tính nhanh
a/1904.(2004-57)-2004.(1904-57)
b/\((\frac{1}{2}-1)\times(\frac{1}{3}-1)\times(\frac{1}{4}-1)\times...\times(\frac{1}{2004}-1)\)1)
c/\(\left(1+2^4+2^8\right):\left(1+2+2^2+2^3+2^4+2^5+2^6+2^7+2^8+2^9+2^{10}+2^{11}\right)\)
tính tổng đại số sau
a] S=1-2-3+4+5-6-7+8+...+2001-2002-2003+2004
b] S=1+2-3-4+5+6-7-8+9+...+2002-2003-2004+2005+2006
a)S= (1-2-3+4)+(5-6-7+8)+....+(2001-2002-2003+2004)=0+0+0+..+000000000000= 0
b)Tương tự a nhưng nhóm 5 sô
giúp mình nha,thanks
tính : 1^2-2^2+3^2-4^2+...-2004^2+2005^2
b) (2+1)(2^2+1)(2^4+1)(2^8+1)(2^16+1)(2^32+1)-2^64
bài 6:tính nhanh
7)1\(^2\)-2\(^2\)+3\(^2\)-4\(^2\)+....-2004\(^2\)+2005\(^2\)
8) (2+1)(2\(^2\)+1)(2\(^4\)+1)(2\(^8\)+1)(2\(^{16}\)+1)(2\(^{32}\)+1)-2\(^{64}\)
7) \(A=1^2-2^2+3^2-4^2+...-2004^2+2005^2\)
\(A=\left(-1\right)\left(1^{ }+2\right)+\left(-1\right)\left(3+4\right)+...+\left(-1\right)\left(2003+2004\right)+2005^2\)
\(A=-\left(1+2+3+...+2004\right)+2005^2\)
\(A=-\dfrac{2004.\left(2004+1\right)}{2}+2005^2\)
\(A=-1002.2005+2005^2\)
\(A=2005\left(2005-1002\right)=2005.1003=2011015\)
8) \(B=\left(2+1\right)\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)
\(B=\dfrac{\left(2^2-1\right)}{2-1}\left(2^2+1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)
\(B=\left(2^4-1\right)\left(2^4+1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)
\(B=\left(2^8-1\right)\left(2^8+1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)
\(B=\left(2^{16}-1\right)\left(2^{16}+1\right)\left(2^{32}+1\right)-2^{64}\)
\(B=\left(2^{32}-1\right)\left(2^{32}+1\right)-2^{64}\)
\(B=\left(2^{64}-1\right)-2^{64}\)
\(B=-1\)