CHỨNG MINH: \(\frac{51\times52\times53\times...\times100}{2^{50}}=1\times3\times5\times7\times...\times99\)
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SO SÁNH
C= \(1\times3\times5\times7\times...\times99\) VOI D=\(\frac{51}{2}\times\frac{52}{2}\times\frac{53}{2}\times...\times\frac{100}{2}\)
Tính:
\(M=\frac{1\times2\times3\times4\times5\times6\times7\times8\times9\times...\times97\times98\times99}{10}\)
\(M=\frac{1.2.3.4.5...98.99}{10}\)
\(M=1.2.3.4.5.6.7.8.9.11.12...98.99\)
Giúp mình với!!!!!
Tính:
G=\(\frac{1}{1\times3\times5}+\frac{1}{5\times7\times9}+\frac{1}{9\times11\times13}+...+\frac{1}{49\times51\times53}\)
\(\frac{1}{1x3x5}+\frac{1}{5x7x9}+\frac{1}{9x11x13}+.....+\frac{1}{49x51x53}=\)
\(1-\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}-\frac{1}{9}+.....+\frac{1}{49}-\frac{1}{51}-\frac{1}{53}=\)
\(1-\frac{1}{3}-\frac{1}{7}-....-\frac{1}{51}-\frac{1}{53}=\)
\(\frac{1\times2}{2\times3}+\frac{2\times3}{3\times4}+\frac{3\times4}{4\times5}+...+\frac{98\times99}{99\times100}\)
\(=\frac{1.2}{99.100}\)
\(=\frac{2}{9900}=\frac{1}{4950}\)
\(A=\left[1-\left(\frac{1}{1\times2\times3}+\frac{1}{2\times3\times4}+......+\frac{1}{98\times99\times100}\right)\right]\times\frac{14851}{19800}\)
A = \(\left(1+\frac{1}{1\times3}\right)\times\left(1+\frac{1}{2\times4}\right)\times\left(1+\frac{1}{3\times5}\right)\times....\times\left(1+\frac{1}{5\times7}\right)\)=?
1=3/3=4/4=5/5=...
=> 1+1/1*3=3/1*3=1/1
=> 1+1/2*4=4/2*4=1/2
=>...
Bieu thuc se con lai la 1*1/2*1/3*1/4*1/5
Vay A=1/120
Tính nhanh: D=\(\frac{4}{2\times3\times4}+\frac{4}{3\times4\times5}+\frac{4}{4\times5\times6}+.......+\frac{4}{98\times99\times100}\)
Tính nhanh:
C=\(\frac{3}{2\times3\times4}+\frac{3}{3\times4\times5}+\frac{3}{4\times5\times6}+......+\frac{3}{98\times99\times100}\)
C = \(\frac{3}{2.3.4}+\frac{3}{3.4.5}+.....+\frac{3}{98.99.100}\)
C = \(3.\left(\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{98.99.100}\right)\)
C = \(3.\frac{1}{2}.\left(\frac{2}{2.3.4}+\frac{2}{3.4.5}+...+\frac{2}{98.99.100}\right)\)
C = \(\frac{3}{2}.\left(\frac{4-2}{2.3.4}+\frac{5-3}{3.4.5}+...+\frac{100-98}{98.99.100}\right)\)
C = \(\frac{3}{2}.\left(\frac{4}{2.3.4}-\frac{2}{2.3.4}+\frac{5}{3.4.5}-\frac{3}{3.4.5}+...+\frac{100}{98.99.100}-\frac{99}{98.99.100}\right)\)
C = \(\frac{3}{2}.\left(\frac{1}{2.3}-\frac{1}{3.4}+\frac{1}{3.4}-\frac{1}{4.5}+...+\frac{1}{98.99}-\frac{1}{99.100}\right)\)
C = \(\frac{3}{2}.\left(\frac{1}{2.3}-\frac{1}{99.100}\right)\)
C = \(\frac{3}{2}.\frac{1649}{9900}\)
C = \(\frac{1649}{6600}\)
Hồ Thu Giang cần chứ nếu được cảm ơn nha
tìm x biết
\(\frac{x\times\left(1\times2+2\times3+3\times4+...+98\times99\right)}{98\times100\times33}=2010-|-2011|\)