Mình chỉ làm được bài b thôi :
2011 x 2012 + 794 / 2011 x 2013 - 1217
= 2011 x 2012 + 794 / 2011 x 2012 + 2011 - 1217
= 2011 x 2012 + 794 / 2011 x 2012 + 794
= 1
Tinh nhanh \(\frac{18\times123+9\times4567\times2+3\times5310\times6}{\left(2+4+6+8+...+18+20+22\right)+48}\)
Tính tổng sau, biết : \(A=\frac{0,18\times1230+0,9\times4567\times2+3\times5310\times0,6}{1+4+7+10+...+52+55+58-440}\)
Tính K + 2013, biết:
K=\(\frac{1+\left(1+2\right)+\left(1+2+3\right)+...+\left(1+2+3+...+2013\right)}{2013\times1+2012\times2+2011\times3+...+2\times2012+1\times2013}\)
cho K=\(\frac{1+\left(1+2\right)+\left(1+2+3\right)+...+\left(1+2+3+...+2012\right)}{2012\times1+2011\times2+2010\times3+...+2\times2011+1\times2012}\)
Tính k +2011
giúp nha -.- mk cho 5 tk
\(1\times2+2\times3+3\times4+4\times5+......+2011\times2012\)
Tính (Theo mẫu):
MẪU\(\frac{9}{10}\times\frac{5}{6}=\frac{9\times5}{10\times6}=\frac{3\times3\times5}{5\times2\times3\times2}=\frac{3}{4}\)\(\frac{3}{4}\)
\(\frac{12}{35}\div\frac{35}{25}\)
\(\frac{9}{22}\times\frac{33}{18}\)
Tính nhanh:\(\frac{1\times2\times3+2\times4\times6+3\times6\times9+4\times8\times12+5\times10\times15}{1\times3\times5+2\times6\times10+3\times9\times15+4\times12\times20+5\times15\times25}-\frac{1+2+3+2+4+6+3+6+9+4+8+12+5+10+15}{1+3+5+2+6+10+3+9+15+4+12+20+5+15+25}\)
tính nhanh:
a]1+4+7+10+....+52+55+58-410
b]1*2+2*3+3*4+....+98*99
c]1/7+1/8+1/9+1/10+1/11+1/12+1/14+1/15+1/18+1/22+1/24+1/28+1/33
Tính nhanh
A=1×5×6+2×10×12+24×8×10/1×35+2×6×10+8×6×20
B=2006×2008-3/2005+2005×2008
C=18×123+9×4567×2+3×5310×6/1+4+7+.......+55+58-410
