(1/2:50%-1/4:25%+1/8:12,5%-1/10:10%):(1+2+3+....+2006+2007+2008)=?
NEU DUNG MINH TIK CHO
Tính nhanh:
a) (1/2 : 50% - 1/4 : 25% + 1/8 : 12,5 - 1/10 : 10%) : 1 + 2 + 3 + ... 2006 + 2007 + 2008)
c) 8,1 : 0,6 x 1875 + 1,5 x 625 x 9
a: \(=\dfrac{\left(\dfrac{1}{2}:\dfrac{1}{2}-\dfrac{1}{4}:\dfrac{1}{4}+\dfrac{1}{8}:\dfrac{1}{8}-\dfrac{1}{10}:\dfrac{1}{10}\right)}{1+2+3+...+2008}\)
=0
c: =8,1*5/3*1875+13,5*625
=13,5(1875+625)
=13,5*2500
=33750
1. So sánh:
a) 11^ 1979 và 37^1320
b) 1990^10 + 1990^9 và 1991^10
c) 10^10 và 48. 50^5
d) A= 2008^2008 +1/ 2008^2009 +1 và B= 2008^2007+1/ 2008^2008 +1
2. Cm:
a) 5^2008 +5^2007 +5^2006 chia hết cho 31
b) 8^8 +2^20 chia hết cho 17
c) 313^ 5. 299- 313^6. 36 chia hết cho 7
HELP ME QUICKLY! Nhanh nha
Bài 2:
a: \(5^{2008}+5^{2007}+5^{2006}\)
\(=5^{2006}\left(5^2+5+1\right)=5^{2006}\cdot31⋮31\)
b: \(8^8+2^{20}\)
\(=2^{24}+2^{20}\)
\(=2^{20}\left(2^4+1\right)=2^{20}\cdot17⋮17\)
1+2-3-4+5-6-7-8+9+10-...+2006-2007-2008+2009
Đặt A=1+2-3-4+5-6-7-8+9+10-...+2006-2007-2008+2009
Ta có:A=1+2-3-4+5+6-7-8+9+10-...+2006-2007-2008+2009
A=1+(2-3-4+5)+(6-7-8+9)+...+(2006-2007-2008+2009)
A=1+0+0+0+....+0
A=1
Ta có:1+2-3-4+5+6-7-8+9+10-...+2006-2007-2008+2009=1+(2-3-4+5)+(6-7-8+9)+...+(2006-2007- 2008+2009)
=1+0+0+0+....+0
=1
tính: 1+2-3-4+5+6-7-8+9+10-...+2006-2007-2008+2009
= 1+(2-3-4+5)+(6-7-8+9)+ ... +(2006-2007-2008+2009)
=1+0+0+ ... +0
=1
1+2-3-4+5+6-7-8+9+10...+2005+2006-2007-2008+2009
\(1+2-3-4+5+6-7-8+...-2007-2008+2009\)
\(=\left(1+2-3-4\right)+\left(5+6-7-8\right)+...+\left(2005+2006-2007-2008\right)+2009\)
\(=\left(-4\right)+\left(-4\right)+\left(-4\right)+...+\left(-4\right)+2009\)
\(=\left(-4\right)\cdot502+2009\)
\(=\left(-2008\right)+2009\)
\(=1\)
1 + 2 - 3 - 4 + 5 + 6 - ... + 2006 - 2007 - 2008 + 2009
= 1 + ( 2 - 3 - 4 + 5 ) + ( 6 - 7 - 8 + 9 ) + ... + ( 2006 - 2007 - 2008 + 2009 )
= 1 + 0 + 0 + ... + 0
= 1
1+2-3-4+5+6-7-8+9+10-11-12+...+2005+2006-2007-2008
Tính tổng:1+2-3-4+5+6-7-8+9+10-...+2006-2007-2008+2009.
Tính
A=1-2+3+4-5-6+7+8-9-.....+2007+2008-2009-2010
B=2^2005-2^2003-2^2001-......-2-1
C=2+4+4+8+10-12-14+16+......-2006+2008+2010-2012
D=1-2-3-4+5-6-7-8+9-10-11-......-2010
Tính : 1+2-3-4+5+6-7-8+9+10-11-12+......+2006-2007-2008+2009
= 1 + (2- 3 - 4 + 5) + (6 - 7 - 8 + 9) + (10 - 11 - 12 + 13) + ...+ (2006 - 2007 - 2008 + 2009)
= 1 + 0 + 0 + 0 + ...+ 0 = 1