2007+2006+2005+2004+....+5+4+3+2+1
Tính:
a) (2^2007 + 2^2006) : 2^2006 b) (3^2011 + 3^2010) : 3^2010
c) (5^2001 + 5^2000) : 5^2000 d) (4^2001 + 4^2000) : 4^2000
e) (6^2005 + 6^2004) : 6^2004 f) (7^2011 + 7^2010) : 7^2010
\(a,\left(2^{2007}+2^{2006}\right):2^{2006}=2^{2007}:2^{2006}+2^{2006}:2^{2006}=2+1=3\\ b,\left(3^{2011}+3^{2010}\right):3^{2010}=3^{2011}:3^{2010}+3^{2010}:3^{2010}=3+1=4\\ c,\left(5^{2001}+5^{2000}\right):5^{2000}=5^{2001}:5^{2000}+5^{2000}:5^{2000}=5+1=6\)
Tương tự là d,e,f và kết quả đúng lần lượt là 5,7,8 nha
So sánh A và B :
a, A = 2006^2006 + 1 / 2006^2007 + 1 và B = 2006^2007 + 1 / 2006^2008 + 1
b, A = 2004 . 2005 - 1 / 2004 . 2005 và B = 2005 . 2006 - 1 / 2005 . 2006
1-2-3+4+5-6-7+8+2011-2002-2003+2004+2005-2006-2007+2008+2009=
Tính nhanh:
=(1-2-3+4)+(5-6-7+8)+...+(2005-2006-2007+2008)+2009
=2009
CHO a/b = c/d . Chứng minh
1) a2004- b2004 / a2004 + b2004 = c2004- d2004 / c2004 + d2004
2) (a2004+ b 2004) 2005/(c2004+d2004) 2005 = (a2005 - b 2005) 2004/ (c2005 - d2005) 2004
3) (20a2006 +11b2006) 2007 /(20a200711b2007) 2006
= (20c2006+ 11d2006) 2007 / (20c2007- 11d 2007)2006
\(\frac{\frac{2006}{2}+\frac{2006}{3}+\frac{2006}{4}+...........+\frac{2006}{2007}}{\frac{2006}{1}+\frac{2005}{2}+\frac{2004}{3}+.............+\frac{1}{2006}}\)
Đặt biểu thức là A ta có:
\(A=\frac{\frac{2006}{2}+\frac{2006}{3}+\frac{2006}{4}+...+\frac{2006}{2007}}{\frac{2006}{1}+\frac{2005}{2}+\frac{2004}{3}+...+\frac{1}{2006}}\)
\(\Rightarrow A=\frac{2006.\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2007}\right)}{1+\left(1+\frac{2005}{2}\right)+\left(1+\frac{2004}{3}\right)+...+\left(1+\frac{1}{2006}\right)}\)
\(\Rightarrow A=\frac{2006.\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2007}\right)}{1+\frac{2007}{2}+\frac{2007}{3}+...+\frac{2007}{2006}}\)
\(\Rightarrow A=\frac{2006.\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2007}\right)}{2007.\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2006}+\frac{1}{2007}\right)}\)
\(\Rightarrow A=\frac{2006}{2007}\)
C= \(\dfrac{\dfrac{2006}{2}+\dfrac{2006}{3}+\dfrac{2006}{4}+.....+\dfrac{2006}{2007}}{\dfrac{2006}{1}+\dfrac{2005}{2}+\dfrac{2004}{3}+.....+\dfrac{1}{2006}}\)
GIÚP mình nha
Lèm ơn đấy !!!!!
Ta có: \(C=\dfrac{\dfrac{2006}{2}+\dfrac{2006}{3}+\dfrac{2006}{4}+...+\dfrac{2006}{2007}}{\dfrac{2006}{1}+\dfrac{2005}{2}+\dfrac{2004}{3}+...+\dfrac{1}{2006}}\)
\(=\dfrac{\dfrac{2006}{2}+\dfrac{2006}{3}+\dfrac{2006}{4}+...+\dfrac{2006}{2007}}{1+\left(1+\dfrac{2005}{2}\right)+\left(1+\dfrac{2004}{3}\right)+...+\left(1+\dfrac{1}{2006}\right)}\)
\(=\dfrac{\dfrac{2006}{2}+\dfrac{2006}{3}+\dfrac{2006}{4}+...+\dfrac{2006}{2007}}{\dfrac{2007}{2007}+\dfrac{2007}{2}+\dfrac{2007}{3}+...+\dfrac{2007}{2006}}\)
\(=\dfrac{2006}{2007}\)
Tính S
1/ S= 1+3+5+7+9+.........+2001+2003+2005+2007
2/ S = (-2)+(-4)+(-6)+..........+(-2004)+(-2006)+(2008)
CHO a/b = c/d . Chứng minh
1) a2004- b2004 / a2004 + b2004 = c2004- d2004 / c2004 + d2004
2) (a2004+ b 2004) 2005/(c2004+d2004) 2005 = (a2005 - b 2005) 2004/ (c2005 - d2005) 2004
3) (20a2006 +11b2006) 2007 /(20a200711b2007) 2006
= (20c2006+ 11d2006) 2007 / (20c2007- 11d 2007)2006
GIÚP MÌNH VS NHÉ
uk . mk thấy bạn đăng nhưng ko ai trả lời thì mk đăng hộ vs cả bài này mk cũng biết làm hihi
Tính nhanh
a)12/5 × 8 - 4 × 14 /5
b ) 2005 × 2007 - 1 / 2004 + 2005 ×2006