tinh : (1.2 +2.3+3.4+...+2010.2011.2011+2012) +( 1+2+3+...+2011+2012) =
Những câu hỏi liên quan
($\frac{1}{1.2}$ + $\frac{1}{2.3}$ + $\frac{1}{3.4}$ + ... + $\frac{1}{2011. 2012}$ ) x = 2011
\(\Leftrightarrow x\cdot\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{2011}-\dfrac{1}{2012}\right)=2011\)
\(\Leftrightarrow x\cdot\dfrac{2011}{2012}=2011\)
hay x=2012
Đúng 5
Bình luận (0)
\(\left(\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+...+\dfrac{1}{2011.2012}\right)x=2011\)
\(\left(\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{2011}-\dfrac{1}{2012}\right)x=2011\)
\(\left(\dfrac{1}{1}-\dfrac{1}{2012}\right)x=2011\)
\(\dfrac{2011}{2012}x=2011\)
\(x=2012\)
Đúng 4
Bình luận (0)
`(1/[1.2]+1/[2.3]+1/[3.4]+....+1/[2011.2012])x=2011`
`(1-1/2+1/2-1/3+1/3-1/4+.....+1/2011-1/2012)x=2011`
`(1-1/2012)x=2011`
`2011/2012x=2011`
`x=2011:2011/2012`
`x=2012`
Đúng 5
Bình luận (0)
Xem thêm câu trả lời
$A=\frac{2011}{1.2}+\frac{2011}{3.4}+\frac{2011}{5.6}+...+\frac{2011}{1999.2000}$
$B=\frac{2012}{1001}+\frac{2012}{1002}+\frac{2012}{1003}+...\frac{2012}{2000}$
So sánh A với B:
a:A=-2012/4025;B=-1999/3997
b:A=2011/1.2+2011/3.4+.....+2011/1999.2000; B=2012/1001+2012+1002+...+2012/2000
1. Tinh a left(6^9.2^{10}+12^{10}right)+left(2^{19}.27^3+15.4^9.9^4right)2. So sanh A va B.a) Afrac{-2012}{4025};Bfrac{-1999}{3997}b) A3^{21};B2^{31}c) Afrac{2011}{1.2}+frac{2011}{3.4}+frac{2011}{5.6}+....+frac{2011}{1999.2000};Bfrac{2012}{1001}+frac{2012}{1002}+frac{2012}{1003}+....+frac{2012}{2000}
Đọc tiếp
1. Tinh a \(\left(6^9.2^{10}+12^{10}\right)+\left(2^{19}.27^3+15.4^9.9^4\right)\)
2. So sanh A va B.
a) \(A=\frac{-2012}{4025};B=\frac{-1999}{3997}\)
b) \(A=3^{21};B=2^{31}\)
c) \(A=\frac{2011}{1.2}+\frac{2011}{3.4}+\frac{2011}{5.6}+....+\frac{2011}{1999.2000};\)\(B=\frac{2012}{1001}+\frac{2012}{1002}+\frac{2012}{1003}+....+\frac{2012}{2000}\)
1/ (69.210+1210)+(219.273+15.49.94) = 29.39.210+310.220+219.39+5.3.218.38 = 219.39+310.220+219.39+5.218.39
= 218.39(2+3.22+5)=19.218.39
Đúng 0
Bình luận (0)
sao bạn lại nhắn vớ va vớ vậy PHẠM ĐỨC PHÚC
Đúng 0
Bình luận (0)
1/ (69
.210+1210
)+(219
.273+15.49
.94
) = 29
.39
.210+310
.220+219
.39+5.3.218
.38
= 219
.39+310
.220+219
.39+5.218
.39
= 2
18
.39
(2+3.22+5)=19.218
.39
So sánh
A=2011/1.2+ 2011/3.4+2011/5.6+...+2011/1999.2000
B=2012/1001+2012/1002+2012/1003+...+2012/2000
Giups mk với mk cần gấp lắm
A=2011/1.2+2011/3.4+2011/4.5+...+2011/1999.2000
B=2012/1001+2012/1002+2012/1003+...+2012/2000
So sánh A và B
Giúp Mk cho tick lun Thx
Theo bài ra ta có :
\(A=\frac{2011}{1.2}+\frac{2011}{3.4}+\frac{2011}{4.5}+...+\frac{2011}{1999.2000}\)
\(\Rightarrow\frac{A}{2011}=\frac{1}{1.2}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{1999.2000}\)
\(\Rightarrow\frac{A}{2011}=\frac{1}{1}-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{1999}-\frac{1}{2000}\)
\(\Rightarrow\frac{A}{2011}=\left(\frac{1}{1}+\frac{1}{3}+...+\frac{1}{1999}\right)+\left(\frac{1}{2}+\frac{1}{4}+\frac{1}{2000}\right)\)
\(\Rightarrow\frac{A}{2011}=\left(\frac{1}{1}+\frac{1}{2}+...+\frac{1}{2000}\right)-\left(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{2000}\right)\) \(-\left(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{2000}\right)\)
\(\Rightarrow\frac{A}{2011}=\left(\frac{1}{1}+\frac{1}{2}+...+\frac{1}{2000}\right)-2\left(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{2000}\right)\)
\(\Rightarrow\frac{A}{2011}=\left(\frac{1}{1}+\frac{1}{2}+...+\frac{1}{2000}\right)-\left(\frac{1}{1}+\frac{1}{2}+...+\frac{1}{1000}\right)\)
\(\Rightarrow\frac{A}{2011}=\frac{1}{1001}+\frac{1}{1002}+...+\frac{1}{2000}\)
\(\Rightarrow A=2011\left(\frac{1}{1001}+\frac{1}{1002}+...+\frac{1}{2000}\right)\left(1\right)\)
Ta lại có :
\(B=\frac{2012}{1001}+\frac{2012}{1002}+...+\frac{2012}{2000}\)
\(\Rightarrow B=2012\left(\frac{1}{1001}+\frac{1}{1002}+...+\frac{1}{2000}\right)\)\(\left(2\right)\)
Từ (1) và (2) => A < B
Vậy A < B
Câu 1:So sánh M= 1/1.2+1/2.3+...+1/49.50 với 1
Câu 2: Tính. B=1+2+2^2+2^3+...+2^2008/1-2^2009
Câu 3.Tính. B=1/2+1/6+1/12+1/20+1/30+...+1/9900
Câu 4.Tính. 1/1.3+1/3.5+1/5.7+...+1/2009.2011
Câu 5. So sánh:
A=2011+2012/2012+2013
Và B=2011/2012+2011/2012+2012/2013
Câu 6: Tìm x biết :.(x/7+0,25)=-1/28
so sánh A = 2011/1.2 +2011/3.4 +...+2011/1999.2000 ; B = 2012/1001 +2012/1002 +...+2012/2000
Giải Pt :
a) \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+........+\frac{1}{x\left(x+1\right)}=\frac{\sqrt{2012-x}+2012}{\sqrt{2012-x}+2013}\)
b) \(\sqrt{2x+3}+\sqrt{x+1}=3x+2\sqrt{2x^2+5x+3}-16\)
b) \(\left(\sqrt{2x+3}-3\right)+\left(\sqrt{x+1}-2\right)+5=3x+2\left(\sqrt{2x^2+5x+3}-6\right)+12-16\)
\(\Leftrightarrow\left(\sqrt{2x+3}-3\right)+\left(\sqrt{x+1}-2\right)=3\left(x-3\right)+2\left(\sqrt{2x^2+5x+3}-6\right)\)
\(\Leftrightarrow\frac{2\left(x-3\right)}{\sqrt{2x+3}+3}+\frac{x-3}{\sqrt{x+1}+2}-3\left(x-3\right)-\frac{2\left(x-3\right)\left(2x+11\right)}{\sqrt{2x^2+5x+3}+6}=0\Leftrightarrow x-3=0\Leftrightarrow x=3.\)
Đúng 0
Bình luận (0)