Tính C=\(\left(1-\frac{1}{1+2}\right)-\left(1-\frac{1}{1+2+3}\right)-...-\left(1-\frac{1}{1+2+...+2018}\right)\)
CON LẠY MẤY THÁNH GIÚP CON VỚI
1.Tính
\(A=\frac{\left(1+17\right)\left(1+\frac{17}{2}\right)\left(1+\frac{17}{3}\right)+...+\left(1+\frac{17}{19}\right)}{\left(1+19\right)\left(1+\frac{19}{2}\right)\left(1+\frac{19}{3}\right)+...+\left(1+\frac{19}{17}\right)}\)
Thánh nào giúp mk với
cho công thức tổng quát nè (do tui tự nghĩ ra đó :))
\(\left(a+b\right)\left(\frac{1}{?}\right)=\frac{a+b}{?}\) dựa vô đây nhân (1+17) và (1+19) và từng cái ngoặc kia là đc
\(A=\frac{\frac{1+17}{1}\cdot\frac{2+17}{2}\cdot\frac{3+17}{3}\cdot...\cdot\frac{19+17}{19}}{\frac{1+19}{1}\cdot\frac{2+19}{2}\cdot\frac{3+19}{3}\cdot...\cdot\frac{17+19}{17}}=\frac{18\cdot19\cdot20\cdot...\cdot36}{1\cdot2\cdot3\cdot...\cdot19}:\frac{20\cdot21\cdot22\cdot...\cdot36}{1\cdot2\cdot3\cdot...\cdot17}\)
\(=\frac{18\cdot19}{18\cdot19}=1\)
Thực hiện phép tính:
a, A= \(\frac{1}{6}.\left(-2\frac{3}{5}\right)+1\frac{2}{3}.\left(\frac{-13}{5}\right)\)
b, B=\(\frac{5}{7}:\left(\frac{1}{2}-\frac{1}{3}\right)+\frac{5}{7}:\left(\frac{1}{5}-\frac{1}{6}\right)\)
c, C= \(2^3+3.\left(\frac{2017}{2018}\right)^0.\left(\frac{1}{2}\right)^{-2}:4+[\left(-2\right)^2:\frac{1}{2}].\left(\frac{-1}{2}\right)^3\)
giúp vs, mik cần gấp
A= E387E4837
B = 883433
C = UỲUWFHQWURY48E3947
Tính:
\(P=\left(1-\frac{1}{1+2}\right)\left(1-\frac{1}{1+2+3}\right)....\left(1-\frac{1}{1+2+3+...+2018}\right)\)
MÌNH ĐANG RẤT CẦN CÁC BẠN GIÚP MÌNH VỚI
â , tính M = \(\left(1+\frac{1}{2}\right)\left(1+\frac{1}{3}\right).......\left(1+\frac{1}{2017}\right)\left(1+\frac{1}{2018}\right)\)
b , Cho A = \(1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+.....+\frac{1}{2017}-\frac{1}{2018}\)
c , B = \(\frac{1}{1010}+\frac{1}{1011}+.....+\frac{1}{2017}+\frac{1}{2018}.tinh\left(\frac{A}{B}\right)^{2018}\)
a, \(M=\frac{3}{2}\cdot\frac{4}{3}\cdot\cdot\cdot\cdot\frac{2018}{2017}\cdot\frac{2019}{2018}=\frac{3.4...2019}{2.3...2018}=\frac{2019}{2}\)
b, c cùng 1 câu phải k
ta có: \(A=1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2017}-\frac{1}{2018}\)
\(=\left(1+\frac{1}{3}+...+\frac{1}{2017}\right)-\left(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{2018}\right)\)
\(=\left(1+\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2018}\right)-2\left(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{2018}\right)\)
\(=1+\frac{1}{2}+...+\frac{1}{2018}-\left(1+\frac{1}{2}+...+\frac{1}{1009}\right)\)
\(=\frac{1}{1010}+\frac{1}{1011}+...+\frac{1}{2018}=B\)
\(\Rightarrow\frac{A}{B}=1\Rightarrow\left(\frac{A}{B}\right)^{2018}=1^{2018}=1\)
A,\(M=\frac{3}{2}\cdot\frac{4}{3}....\frac{2018}{2017}\cdot\frac{2019}{2018}=\frac{4\cdot3...2019}{2\cdot3...2018}=\frac{2019}{2}\)
NHA
HỌC TỐT
Thực hiện phép tính:\(\left(1-\frac{1}{2018}\right).\left(1-\frac{2}{2018}\right).\left(1-\frac{3}{2018}\right)...\left(1-\frac{2020}{2018}\right)\)
tính A biết
A=\(\left(\frac{1}{1+2}-1\right)\times\left(\frac{1}{1+2+3}-1\right)\times\left(\frac{1}{1+2+3+4}-1\right)\times...\times\left(\frac{1}{1+2+3+4+...+2018}-1\right)\)
Giúp mình nhanh nha các bạn
Tính \(B=1+\frac{1}{2}\left(1+2\right)+\frac{1}{3}\left(1+2+3\right)+...+\frac{1}{2018}\left(1+2+3+...+2018\right)\)
\(B=1+\frac{1}{2}.\frac{\left(1+2\right).2}{2}+\frac{1}{3}.\frac{\left(1+3\right).3}{2}+...+\frac{1}{2018}.\frac{\left(1+2018\right).2018}{2}\)
\(=1+\frac{3}{2}+\frac{4}{2}+...+\frac{2019}{2}=1+\frac{3+4+...+2019}{2}=1+\frac{\left(3+2019\right)2017}{2}=2039188\)
1, Tính giá trị biểu thức :
\(a,A=5\frac{9}{10}:\frac{3}{2}-\left(2\frac{1}{3}.4\frac{1}{2}-2.2\frac{1}{3}\right):\frac{7}{4}\)
\(b,B=\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right).............\left(1-\frac{1}{2017}\right).\left(1-\frac{1}{2018}\right)\)
Mọi người giúp mình giả toán nha !
Ta có:
\(B=\left(1-\frac{1}{2}\right).\left(1-\frac{1}{3}\right).\left(1-\frac{1}{4}\right)........\left(1-\frac{1}{2017}\right).\left(1-\frac{1}{2018}\right)\)
\(\Rightarrow B=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.......\frac{2016}{2017}.\frac{2017}{2018}\)
Đởn giản hết sẽ còn là:
\(\Rightarrow B=\frac{1}{2018}\)
bài 1: tính
\(A=\frac{4^2-3x+17}{x^3-1}+\frac{2x-1}{x^2+x+1}+\frac{6}{1-x}\)
\(B=\frac{3x+1}{x^2-2x+1}-\frac{1}{x+1}+\frac{x+3}{1-x^2}\)
\(C=\left(\frac{x}{x+1}+1\right):\left(1-\frac{3x^2}{1-x2}\right)\)
\(D=\left(\frac{x^2}{y^2}+\frac{y}{x}\right):\left(\frac{x}{y^2}-\frac{1}{y}+\frac{1}{x}\right)\)
\(E=\left(\frac{1}{x^2+4x+4}-\frac{1}{x^2-4x+4}\right):\left(\frac{1}{x+2}+\frac{1}{x-2}\right)\)
\(F=\frac{1}{x-1}-\frac{x^3-x}{x^2+1}\left(\frac{1}{x^2-2x+1}+\frac{1}{1-x^2}\right)\)
Mấy thánh ơi giúp em với mai phải nộp rồi!!!!!!!!!!!!!!!