Tính tổng:
A=(5^2007-5^2006):(5^2006.5)
tính nhanh
(52007-52006):(52005.5)
(52007-52006):(52005.5)
=52006(5-1):52006
=52006:52006.4
=4
(52007-52006):(52005.5)
=52007-52006:52006=52007-(52006:52006)
=52007-1
thực hiện phép tính (5^2007 - 5^2006) : (5^2005 . 5 )
1513 : 1510 + 32.246 - 152.23
a) \(\left(5^{2007}-5^{2006}\right)\div\left(5^{2005}.5\right)\)
\(=\left(5^{2007}-5^{2006}\right)\div5^{2006}\)
\(=5^{2007}\div5^{2006}-5^{2006}\div5^{2006}\)
\(=5-1=4\)
Tìm x để thỏa mãn đẳng thức: x+6/2006+x+5/2007+x+4/2008=X+2006/6+x+2007/5+x+2008/4
Cho A = 2007 x 2007 x ... x 2007 x 2007 ( có 2006 thừa số 2007 )
Cho B = 2006 x 2006 x … x 2006 x2006 ( có 2007 thừa số 2006 )
Hãy cho biết hiệu A và B có chia hết cho 5 không ? Tại sao ?
Ta co
A=2007^2006( lên lơp 6 e se hoc)
=>A=2007^2 x 2007^2004
=>(...9)x(...1)=(...9) (1)
Ta co:
B=2006^2007=(...6)
A=....9
B=....6
A-B= ....9- ....6= ....3 không chia hết cho 5
=> A-B=(...9)-(...6)=(...3) khong chi het cho 5
Tính nhanh
a)12/5 × 8 - 4 × 14 /5
b ) 2005 × 2007 - 1 / 2004 + 2005 ×2006
Tính : 1+2-3-4+5+6-7-8+.....+2006-2007-2008+2009
2008+2007/2+2006/3+2005/4+2005/5+........................3/2006+2/2007+1/2008
1/2+1/3+1/4+1/5+....................+1/2009
2008-1/2008=2007/2008
1/2-1/2009=2007/2009
2008+2007/2+2006/3+2005/4+2005/5+........................3/2006+2/2007+1/2008
1/2+1/3+1/4+1/5+....................+1/2009
1 Tính
A (1-1/2) * (1-1/3 ) * (1-1/4 ) * .....*(1-1/19)* ( 1-1/20)
B 3/2 * 4/3 * 6/5* ......* 2006/2005 * 2007/2006 * 2008/2007
\(A=\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot......\cdot\left(1-\frac{1}{20}\right)\)
\(A=\frac{1}{2}\cdot\frac{2}{3}\cdot......\cdot\frac{19}{20}\)
\(A=\frac{1.2.3.....19}{2.3........20}\)
\(A=\frac{1}{20}\)