\(\left(\frac{3}{429}-\frac{1}{1.3}\right)\left(\frac{3}{429}-\frac{1}{3.5}\right)....\left(\frac{3}{429}-\frac{1}{119.121}\right)\left(\frac{3}{429}-\frac{1}{121.123}\right)\)= ?
(3/429 - 1/1.3)(3/429 - 1/3.5) ... (3/429 - 1/121.123)
= (1/143 - 1/1.3)(1/143 - 1/3.5) ... (1/143 - 1/11.13) ... (1/143 - 1/121.123)
= (1/11.13 - 1/1.3)(1/11.13 - 1/3.5) ... (1/11.13 -1/11.13) ... (1/11.13 - 1/121.123)
= (1/11.13 - 1/1.3)(1/11.13 - 1/3.5) ... 0 ... (1/11.13 - 1/121.123)
= 0
=(1/143-1/1.3)...(1/143-1/121.123)
vì trong tích có thừa số (1/143-1/11.13)=0
nên cả tích =0
LÀM ƠN LIKE CHO MÌNH ĐI
tính A= \(\left(\frac{3}{429}-\frac{1}{1.3}\right).\left(\frac{3}{429}-\frac{1}{3.5}\right)..........\left(\frac{3}{429}-\frac{1}{121.123}\right)\)
\(\frac{1}{1.2}+\frac{1}{3.4}+\frac{1}{5.6}+...+\frac{1}{49.50}=\frac{1}{26}+\frac{1}{27}+...+\frac{1}{50}\)
b. \(\frac{1}{4}+\frac{1}{16}+\frac{1}{36}+...+\frac{1}{196}<2\)
tính tích\(\left(\frac{3}{429}-\frac{1}{1.3}\right).\left(\frac{3}{429}+\frac{1}{3.5}\right).........\left(\frac{3}{429}-\frac{1}{119.121}\right)+\left(\frac{3}{429}-\frac{1}{121.123}\right)\)
Tính tích:
\(A=\left(\frac{3}{429}-\frac{1}{1\times3}\right)\times\left(\frac{3}{429}-\frac{1}{3\times5}\right)\times...\times\left(\frac{3}{429}-\frac{1}{119\times121}\right)\times\left(\frac{1}{429}-\frac{2}{121\times123}\right)\)
(3/429 - 1/1.3)(3/429 - 1/3.5) ... (3/429 - 1/121.123)
= (1/143 - 1/1.3)(1/143 - 1/3.5) ... (1/143 - 1/11.13) ... (1/143 - 1/121.123)
= (1/11.13 - 1/1.3)(1/11.13 - 1/3.5) ... (1/11.13 -1/11.13) ... (1/11.13 - 1/121.123)
= (1/11.13 - 1/1.3)(1/11.13 - 1/3.5) ... 0 ... (1/11.13 - 1/121.123)
= 0
Ai giải được bài này sẽ là học sinh giỏi(tất nhiên là mình giải được)
\(\left(\frac{3}{429}-\frac{1}{1\cdot3}\right)\left(\frac{3}{429}-\frac{1}{3\cdot5}\right)...\left(\frac{3}{429}-\frac{1}{20015\cdot20017}\right)\left(\frac{3}{429}-\frac{1}{20017\cdot20019}\right)\)
Nó thì cô giải cho rồi, nó biết là phải
bài này dễ mà nhóm 3/429 ra có rồi khử liên tiếp
(\(\frac{3}{429}\)-\(\frac{1}{1.3}\)).(\(\frac{3}{429}\)-\(\frac{1}{3.5}\)).......(\(\frac{3}{429}\)-\(\frac{1}{119.121}\)).(\(\frac{3}{429}\)-\(\frac{1}{121.123}\)) Tính tích
Tính các tích sau:
a)\(A=\frac{3}{4}.\frac{8}{9}.\frac{15}{16}.....\frac{9999}{10000}\)
b)\(B=\left(1-\frac{1}{21}\right).\left(1-\frac{1}{28}\right).\left(1-\frac{1}{36}\right)......\left(1-\frac{1}{1326}\right)\)
c)\(C=\left(1+\frac{1}{1.3}\right).\left(1+\frac{1}{2.4}\right).\left(1+\frac{1}{3.5}\right)....\left(1+\frac{1}{99.101}\right)\)
Tính giá trị các biểu thức sau:
a,A=\(\frac{2}{3}+\frac{5}{6}:5-\frac{1}{18}.\left(-3\right)^2\)
b,B=\(3.\left(5.\left(\left(5^2+2^3\right):11\right)-16\right)+2015\)
c,C=\(\left(1+\frac{1}{1.3}\right)\left(1+\frac{1}{2.4}\right)\left(1+\frac{1}{3.5}\right)...\left(1+\frac{1}{2014.2016}\right)\)
Tìm tích:A=\(\left(\dfrac{3}{429}-\dfrac{1}{1.3}\right).\left(\dfrac{3}{429}-\dfrac{1}{3.5}\right)........\left(\dfrac{3}{429}-\dfrac{1}{119121}\right)\)
GIẢI GIÙM MÌNH NHA
