tính nhanh 3/13/123/123...3/123...10 1/121/1231/1234...1/1234.....50

Question

tính nhanh 3/1+3/1+2+3/1+2+3+...+3/1+2+3+...+10 1/1+2+1/1+2+3+1/1+2+3+4+...+1/1+2+3+4+.....+50

tuyetnhungthu · Answer

(A=3+ frac{3}{1+2}+ frac{3}{1+2+3}+...+ frac{3}{1+2+3+4+...+100} )       (A=3 left(1+ frac{1}{1+2}+ frac{1}{1+2+3}+...+ frac{1}{1+2+3+4+...+100} right) )       (B=1+ frac{1}{1+2}+ frac{1}{1+2+3}+...+ frac{1}{1+2+3+4+...+100} )      (B=1+ frac{1}{1+2}+ frac{1}{1+2+3}+...+ frac{1}{1+2+3+4+...+100} )      (B=1+ frac{1}{ left(1+2 right).2:2}+ frac{1}{ left(1+3 right).3:2}+ frac{1}{ left(1+4 right).4:2}+...+ frac{1}{ left(1+100 right).100:2} )      (B= frac{2}{1.2}+ frac{2}{2.3}+ frac{2}{3.4}+ frac{2}{4.5}+...+ frac{2}{100.101} )      (B=2 left( frac{1}{1.2}+ frac{1}{2.3}+ frac{1}{3.4}+ frac{1}{4.5}+...+ frac{1}{100.101} right) )      (B=2 left(1- frac{1}{2}+ frac{1}{2}- frac{1}{3}+ frac{1}{3}- frac{1}{4}+ frac{1}{4}- frac{1}{5}+...+ frac{1}{100}- frac{1}{101} right) )      (B=2. left(1- frac{1}{101} right) )      (B=2. frac{100}{101}= frac{200}{101} )       Ta c&oacute;:     A=3.B     Rightarrow $A=3. frac{200}{101}= frac{600}{101}$       (A= frac{600}{101} )

tính nhanh 3/1+3/1+2+3/1+2+3+…+3/1+2+3+…+10 1/1+2+1/1+2+3+1/1+2+3+4+…+1/1+2+3+4+…..+50

1 bình luận về “tính nhanh 3/1+3/1+2+3/1+2+3+…+3/1+2+3+…+10 1/1+2+1/1+2+3+1/1+2+3+4+…+1/1+2+3+4+…..+50”

Viết một bình luận Hủy