Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
1/1.2+1/2.3+1/3.4+......+1/2003.2004=1/1-1/2+1/2-1/3+1/3-1/4+......+1/2003-1/2004
=1/1-1/2004
=2003/2004
1/1.2+1/2.3+1/3.4+.......1/2003.2004
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2003}-\frac{1}{2004}\)
\(=1-\frac{1}{2004}\)
\(=\frac{2003}{2004}\)
(1-1/1.2)+(1-1/2*3)+......+(1-1/2015*2016)
=(0/1*2)+(0+2*3)+..........+(0/2015*2016)
=0
tui nghĩ cái đề phải như thế này \(\left(1-\frac{1}{1.2}\right)+\left(1-\frac{1}{2.3}\right)+\left(1-\frac{1}{3.4}\right)+...+\left(1-\frac{1}{2015.2016}\right)\)
S=1.2+2.3+...+39.40
3S=1.2.(3 - 0)+2.3.(4 - 1)+...+39.40.(41 - 38)
3S=1.2.3 - 0.1.2 + 2.3.4 - 1.2.3 +...+ 39.40.41 - 38.39.40
3S=39.40.41
S=13.40.41
S=21320
x-2x+5y-12=0
y(x+5)-2(x+5)-2=0
(y-2)(x+5)=2
xong thu TH nha
k cho toi di Hien beo ne
\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2003.2004}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2003}-\frac{1}{2004}\)
\(=1-\frac{1}{2004}\)
\(=\frac{2003}{2004}\)
\(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{2003\cdot2004}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-...-\frac{1}{2003}+\frac{1}{2003}-\frac{1}{2004}\)
\(=1-\frac{1}{2004}\)
\(=\frac{2003}{2004}\)
a) 15-(x-5)=-1
x-5= 15-(-1)=15+1
x-5= 16
x = 16+5
x=21
b) -39-x=-3-16
-39-x= -19
x=(-39)-(-19)=(-39)+19
x=-20
Học tốt bạn nhé
Trl:
a) \(15-\left(x-5\right)=-1\)
\(\Rightarrow\left(x-5\right)=15-\left(-1\right)\)
\(\Rightarrow\left(x-5\right)=15+1\)
\(\Rightarrow\left(x-5\right)=16\)
\(\Rightarrow x=16+5\)
\(\Rightarrow x=21\)
b) \(-39-x=-3-16\)
\(\Rightarrow-39-x=-19\)
\(\Rightarrow x=-39-\left(-19\right)\)
\(\Rightarrow x=-39+19\)
\(\Rightarrow x=-20\)
\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+.....+\frac{1}{100.101}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+.....+\frac{1}{100}-\frac{1}{101}\)
\(=1-\frac{1}{101}\)\(=\frac{101}{101}-\frac{1}{101}\)
\(=\frac{100}{101}\)
thank you