Tính \(A=\left(1-\frac{2}{5}\right).\left(1-\frac{2}{7}\right).\left(1-\frac{2}{9}\right).....\left(1-\frac{2}{2011}\right)\)
- giải hộ mình ạ :< Nhanh + đúng = Tick -.-
tính :
\(\frac{1,6:\left(1\frac{3}{5}.1,25\right)}{0,64-\frac{1}{25}}+\frac{\left(1,08-\frac{2}{25}\right):\frac{4}{7}}{\left(5\frac{5}{9}-2\frac{1}{4}\right).2\frac{2}{17}}+0,6.0,5:\frac{2}{5}\)( các banmj giải hộ mình nha . giải đúng , chi tiết mình tick)
\(\left(1+\frac{7}{9}\right)\left(1+\frac{7}{20}\right)\left(1+\frac{7}{33}\right)...\left(1+\frac{7}{9200}\right)\)
Giải hộ mình với ạ! Ai làm mình cảm thấy đúng thì mình tick
`Answer:`
Ta thấy:
\(9=1.9\)
\(20=10.2\)
\(33=11.3\)
...
\(9200=100.92\)
`=>` Mẫu thức của từng nhân tử có dạng là \(n\left(n+8\right)\)
Xét dạng tổng quát của nhân tử: \(1+\frac{7}{n\left(n+8\right)}=\frac{n^2+8n+7}{n\left(n+8\right)}=\frac{\left(n+1\right)\left(n+7\right)}{n\left(n+8\right)}\)
\(n=1\Rightarrow1+\frac{7}{1.9}=\frac{2.8}{1.9}\)
\(n=2\Rightarrow1+\frac{7}{2.10}=\frac{3.9}{2.10}\)
\(n=3\Rightarrow1=\frac{7}{3.10}=\frac{4.10}{3.11}\)
...
\(n=92\Rightarrow1+\frac{7}{92.100}=\frac{93.99}{92.100}\)
\(\Rightarrow\frac{2.8}{1.9}.\frac{3.9}{2.10}.\frac{4.10}{3.11}...\frac{93.99}{92.100}=\frac{\left(2.3.4...93\right)\left(8.9.10...9\right)}{\left(1.2.3...92\right)\left(9.10.11...100\right)}=\frac{93.8}{1.100}=\frac{186}{25}\)
\(y=\left(1+\frac{1}{2}\right).\left(1+\frac{1}{3}\right).\left(1+\frac{1}{4}\right).....\left(1+\frac{1}{2010}\right).\left(1+\frac{1}{2011}\right)\)
Tìm y
Giải nhớ có lời giải nhé
Ai làm nhanh mà đúng mình tick cho, hứa luôn
\(A=\frac{1}{2}-\frac{3}{4}+\frac{5}{6}-\frac{7}{12}\)
\(B=3-\frac{2}{3}+\frac{3}{5}\left(-\frac{10}{9}-\frac{25}{3}\right)-\frac{5}{6}\)
\(\left(3-\frac{3}{4}+\frac{2}{3}\right)-\left(2+\frac{4}{3}-\frac{3}{2}\right)-\left(1-\frac{7}{3}-\frac{9}{2}\right)\)
\(D=\left[-\frac{54}{64}-\left(\frac{1}{9}:\frac{8}{27}\right):-\frac{1}{3}\right]:-\frac{81}{128}\)
\(-\frac{3}{5}+\frac{2}{61}-\frac{17}{51}\)
\(\left(\frac{3}{2}-\frac{5}{11}-\frac{3}{13}\right)+\left(\frac{3}{4}+\frac{5}{22}+\frac{3}{26}\right)\)
\(\frac{1}{4}-3\cdot\left(\frac{1}{12}+\frac{3}{8}\right)\)
\(\left(-\frac{2}{3}+\frac{3}{5}\right):\frac{1}{50}-30\)
\(\left(-\frac{4}{5}+\frac{5}{7}\right):\frac{3}{17}+\left(-\frac{1}{5}+\frac{2}{7}\right):\frac{3}{17}\)
\(\frac{1}{3}-\frac{1}{7}+\frac{8}{9}+\frac{15}{12}-\frac{3}{5}-\frac{2}{3}\)
► Các cậu giúp mình nha. Mình sẽ tick cho ai có đáp án nhanh nhất và đúng nhất nhé. Mình cảm ơn tất cả các cậu trước ạ. Kamsa~
Những câu từ D trở đi là các câu riêng biệt ak bạn
\(A = {1\over2}-{3\over4}+{5\over6}-{7\over12}={6\over12}-{9\over12}+{10\over12}-{7\over12}\)\(={0\over12}=0\)
\(B=3-{2\over3}+{3\over5}(-{10\over9}-{25\over3})-{5\over6}\)\(={7\over3}+{3\over5}(-{10\over9}-{75\over9})-{5\over6}\)\(={14\over6}-{5\over6}+{3\over5}({-85\over9})\)\(={3\over2}-{17\over3}={9\over6}-{34\over6}={-25\over6}\)
Tính hợp lí ( nếu có thể)
a,\(\left(\frac{2}{5}-\frac{1}{2}\right)^2-\frac{11}{5}:\frac{-11}{5}\)
b,\(\left(\frac{-5}{7}\right)^2+8\times\left(0,5\right)^2+\left(-1\right)^{2010}\)
\(\frac{9999^2}{3333^2}+\left(0,5\right)^4\times\left(-2\right)^4-\left(\frac{-4}{3}\right)^3\)
\(|\frac{-2}{5}+\frac{1}{7}|:\frac{-3}{35}+\frac{-3}{7}\times\frac{7}{5}\)
\(\frac{1}{2}-\left(-0,4\right)+\frac{1}{3}+\frac{5}{7}-\frac{-1}{6}+\frac{-4}{35}+\frac{1}{41}\)
Mình đang cần gấp lắm ạ . Bạn nào làm đúng và nhanh nhất mình sẽ tick ạ . Cảm ơn và nhờ các bạn giải chi tiết giúp mình với ạ <3
Thanks ^^
a) \(\left(\frac{2}{5}-\frac{1}{2}\right)^2-\frac{11}{5}:\frac{-11}{5}=\left(-\frac{1}{10}\right)^2+1=1\frac{1}{100}\)
b) \(\left(-\frac{5}{7}\right)^2+8.\left(0,5\right)^2+\left(-1\right)^{2010}=\frac{25}{49}+2+1=3\frac{25}{49}\)
c) \(\frac{9999^2}{3333^2}+\left(0,5\right)^2.\left(-2\right)^4-\left(-\frac{4}{3}\right)^2=9+1-\frac{16}{9}=8\frac{2}{9}\)
d) \(\left|-\frac{2}{5}+\frac{1}{7}\right|:\frac{-3}{35}+\frac{-3}{7}.\frac{7}{5}=\frac{9}{35}.\frac{35}{-3}-\frac{3}{5}=-3\frac{3}{5}\)
e) \(\frac{1}{2}-\left(-0,4\right)+\frac{1}{3}+\frac{1}{5}-\frac{-1}{6}+\frac{-4}{35}+\frac{1}{41}\)
\(=\frac{1}{2}+\frac{2}{5}+\frac{1}{3}+\frac{1}{5}+\frac{1}{6}-\frac{4}{35}+\frac{1}{41}=1\frac{732}{1435}\)
Bài 1 Thưc hiện phép tính ( tính nhanh nếu có thể)
a)\(\frac{-1}{24}-\left[\frac{1}{4}-\left(\frac{1}{2}-\frac{7}{8}\right)\right]\)
b)\(\left(\frac{5}{7}-\frac{7}{5}\right)-\left[\frac{1}{2}-\left(\frac{-2}{7}-\frac{1}{10}\right)\right]\)
C)\(\left(\frac{-1}{2}\right)-\left(\frac{-3}{5}\right)+\left(\frac{-1}{9}\right)+\frac{1}{17}-\left(\frac{-2}{7}\right)+\frac{4}{35}-\frac{7}{18}\)
d)\(\left(3-\frac{1}{4}+\frac{2}{3}\right)-\left(5-\frac{1}{3}-\frac{6}{5}\right)-\left(6-\frac{7}{4}+\frac{3}{2}\right)\)
\(C=\left(\frac{3}{5}-\frac{4}{15}\right).\left(\frac{2}{7}-\frac{3}{14}\right)-\left(\frac{5}{9}-\frac{7}{27}\right).\left(1-\frac{3}{5}\right)+\left(1-\frac{11}{12}\right).\left(1+\frac{1}{12}\right)\)
Giải nhanh giùm mình nha các bạn
Tìm x
\(\left(2x+\frac{3}{5}\right)^2-\frac{9}{25}=0\)
\(3\left(3x-\frac{1}{2}\right)^3+\frac{1}{9}=0\)
\(-5\left(x+\frac{1}{5}\right)-\frac{1}{2}\left(x-\frac{2}{3}\right)=\frac{3}{2}x-\frac{5}{6}\)
\(3\left(x-\frac{1}{2}\right)-5\left(x+\frac{3}{5}\right)=-x+\frac{1}{5}\)
giải nhanh hộ mình với, mai mình nộp rồi
\(\left(2x+\frac{3}{5}\right)^2-\frac{9}{25}=0\)
\(\Leftrightarrow\left(2x+\frac{3}{5}\right)^2=\frac{9}{25}\)
\(\Leftrightarrow\left(2x+\frac{3}{5}\right)^2=\left(\frac{3}{5}\right)^2\)
\(\Leftrightarrow\orbr{\begin{cases}2x+\frac{3}{5}=\frac{3}{5}\\2x+\frac{3}{5}=-\frac{3}{5}\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}2x=0\\2x=-\frac{6}{5}\end{cases}}\)
\(\Leftrightarrow\orbr{\begin{cases}x=0\\x=-\frac{3}{5}\end{cases}}\)
_Tần vũ_
\(3\left(3x-\frac{1}{2}\right)^3+\frac{1}{9}=0\)
\(\Leftrightarrow3\left(3x-\frac{1}{2}\right)^3=-\frac{1}{9}\)
\(\Leftrightarrow\left(3x-\frac{1}{2}\right)^3=-\frac{1}{27}\)
\(\Leftrightarrow\left(3x-\frac{1}{2}\right)^3=\left(-\frac{1}{3}\right)^3\)
\(\Leftrightarrow3x-\frac{1}{2}=\frac{-1}{3}\)
\(\Leftrightarrow3x=\frac{1}{6}\)
\(\Leftrightarrow x=\frac{1}{18}\)
_Tần Vũ_
a) \(\left(2x+\frac{3}{5}\right)^2-\frac{9}{25}=0\)
\(\Rightarrow\left(2x+\frac{3}{5}\right)^2=0+\frac{9}{25}\)
\(\Rightarrow\left(2x+\frac{3}{5}\right)^2=\frac{9}{25}\)
\(\Rightarrow\left(2x+\frac{3}{5}\right)^2=\frac{3^2}{5^2}\)
\(\Rightarrow\left(2x+\frac{3}{5}\right)^2=\left(\frac{3}{5}\right)^2\)
\(\Rightarrow\hept{\begin{cases}2x+\frac{3}{5}=\frac{3}{5}\\2x+\frac{3}{5}=-\frac{3}{5}\end{cases}}\)\(\Rightarrow\hept{\begin{cases}2x=\frac{3}{5}-\frac{3}{5}\\2x=-\frac{3}{5}-\frac{3}{5}\end{cases}}\)\(\Rightarrow\hept{\begin{cases}2x=0\\2x=\frac{-6}{5}\end{cases}}\)\(\Rightarrow\hept{\begin{cases}x=0:2\\x=-\frac{6}{5}:2\end{cases}}\)\(\Rightarrow\hept{\begin{cases}x=0\\x=-\frac{3}{5}\end{cases}}\)
b) \(3\left(3x-\frac{1}{2}\right)^3+\frac{1}{9}=0\)
\(\Rightarrow3\left(3x-\frac{1}{2}\right)^3=0-\frac{1}{9}\)
\(\Rightarrow3\left(3x-\frac{1}{2}\right)^3=-\frac{1}{9}\)
\(\Rightarrow\left(3x-\frac{1}{2}\right)^3=-\frac{1}{9}:3\)
\(\Rightarrow\left(3x-\frac{1}{2}\right)^3=-\frac{1}{27}\)
\(\Rightarrow\left(3x-\frac{1}{2}\right)^3=\left(\frac{-1^3}{3^3}\right)\)
\(\Rightarrow\left(3x-\frac{1}{2}\right)^3=\left(-\frac{1}{3}\right)^3\)
\(\Rightarrow3x-\frac{1}{2}=-\frac{1}{3}\)
\(\Rightarrow3x=-\frac{1}{3}+\frac{1}{2}\)
\(\Rightarrow3x=\frac{1}{6}\)
\(\Rightarrow x=\frac{1}{6}:3\)
\(\Rightarrow x=\frac{1}{18}\)
Tính và rút gọn các bài toán nâng cao sau
1.Tính
\(A=\left(1-\frac{1}{5}\right).\left(1-\frac{2}{5}\right).\left(1-\frac{3}{5}\right)...\left(1-\frac{9}{5}\right)\)
2 rút gọn
\(B=\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)...\left(1-\frac{1}{50}\right)\)
Ai nhanh ai đúng mk sẽ tick :) :D
1. Có 1 thừa số là \(1-\frac{5}{5}=0\) nên tích sẽ bằng 0
2.\(B=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.......\frac{49}{50}=\frac{1}{50}\)