Cho A=2015.2016/2015.2016+1 và B=2016.2017/2016.2017+1
So sánh A vs B
Bạn nào giải đc mk sẽ tick
a) Hãy so sánh M=2015.2016-1/2015.2016 với N=2016.2017-1/2016.2017
so sánh:
a) A=\(\frac{2014.2015-1}{2014.2015}\)và C=\(\frac{2015.2016-1}{2015.2016}\)
b)B=\(\frac{2015.2016+1}{2015.2016}\)và D=\(\frac{2016.2017+1}{2016.2017}\)
So sánh :
2015.2016-1
2015.2016
và
2016.2017-1
2016.2017
So sánh: x=2015.2016+2/2015.2016 va y=2016.2017+2/2016.2017
Giúp mik nha cần gấp
Ta có : \(x=\frac{2015.2016+2}{2015.2016}=\frac{2015.2016}{2015.2016}+\frac{2}{2015.2016}=1+\frac{1}{1008.2015}\)
\(y=\frac{2016.2017+2}{2016.2017}=\frac{2016.2017}{2016.2017}+\frac{2}{2016.2017}=1+\frac{1}{1008.2017}\)
Vì \(\frac{1}{1008.2015}>\frac{1}{1008.2017}\)
=> \(1+\frac{1}{1008.2015}>1+\frac{1}{1008.2017}\)
=> \(\frac{2015.2016+2}{2015.2016}>\frac{2016.2017+2}{2016.2017}\)
=> \(x>y\)
Ta có:
x = \(\frac{2015.2016+2}{2015.2016}=\frac{2015.2016}{2015.2016}+\frac{2}{2015.2016}=1+\frac{2}{2015.2016}=1+\frac{1}{2015.1008}\)
y = \(\frac{2016.2017+2}{2016.2017}=\frac{2016.2017}{2016.2017}+\frac{2}{2016.2017}=1+\frac{2}{2016.2017}=1+\frac{1}{1008.2017}\)
Do \(\frac{1}{2015.1008}>\frac{1}{1008.2017}\) => \(1+\frac{1}{2015.1008}>1+\frac{1}{1008.2017}\)
=> x > y
1. So sanh :
a) \(\frac{2015.2016-1}{2016.2015}\) va \(\frac{2016.2017-1}{2016.2017}\)
b) \(\frac{2015.2016}{2015.2016+1}\) va \(\frac{2016.2017}{2016.2017+1}\)
c) \(\frac{33.10^3}{2^3.5.10^3+7000}\) va \(\frac{3774}{5271}\)
a.\(\frac{2015.2016-1}{2015.2016}=1-\frac{1}{2015.2016}\)
\(\frac{2016.2017-1}{2016.2017}=1-\frac{1}{2016.2017}\)
vì \(\frac{1}{2015.2016}>\frac{1}{2016.2017}\)
=>\(-\frac{1}{2015.2016}< -\frac{1}{2016.2017}\)
=>\(1-\frac{1}{2015.2016}< 1-\frac{1}{2016.2017}\)
1.2+2.3+3.4+....+2015.2016+2016.2017
11.2+12.3+13.4+14.5+...+12015.2016+12016.2017
=1−12+12−13+13−14+14−15+...+12015−12016+12016−12017
=1−12017=20162017
1/ Hãy lập tất cả các phân số bằng nhau từ đẳng thức 3.4 = 6.2
2/ CHO \(A=\frac{3n-5}{n+4}\), tìm n thuộc Z để A có giá trị nguyên
3/ TÍnh \(S=\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{2015.2016}+\frac{1}{2016.2017}\)
mk sẽ tick cho bạn nào lm hết, mỗi ngày 3 tick nhé , kb lun ^^
1/
+) \(\frac{3}{6}=\frac{2}{4};\frac{3}{2}=\frac{6}{4};\frac{4}{6}=\frac{2}{3};\frac{4}{2}=\frac{6}{3}\)
2/
\(A=\frac{3n-5}{n+4}=\frac{3n+12-17}{n+4}=\frac{3\left(n+4\right)}{n+4}-\frac{17}{n+4}=3-\frac{17}{n+4}\)
Để A nguyên <=> n + 4 thuộc Ư(17) = {1;-1;17;-17}
n+4 | 1 | -1 | 17 | -17 |
n | -3 | -5 | 13 | -21 |
Vậy...
3/
\(S=\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{2016.2017}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{2016}-\frac{1}{2017}\)
\(=1-\frac{1}{2017}\)
\(=\frac{2016}{2017}\)
\(A=\frac{3n+12-7}{n+4}=\frac{3\left(n+4\right)}{n+4}-\frac{7}{n+4}=3-\frac{7}{n+4}\)
=> n-4 \(\in\) Ư (7)
n-4=1
n=4+1=5
n-4=-1
n=-1+4=3
n-4=7
n=4+7=11
n-4=-7
n=-7+4=-3
\(S=\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{2015.2016}+\frac{1}{2016.2017}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{2015}-\frac{1}{2016}+\frac{1}{2016}-\frac{1}{2017}\)
\(=1-\frac{1}{2017}\)
\(=\frac{2016}{2017}\)
P/s:/=phần(phân số)
Bài 1:so sánh các phân số:
a,A=2015/2016 và B=2026/2017
b,C=1/(31)+1/(32)+1/(33)+...+1/(89)+
1/(90) và D=5/6
c,E=(2015.2016-1)/(2015.2016) và
F=(2016.2017-1)/(2016/2017)
d,G=(10^11)-1/(10^12)-1 và
H=(10^10)+1/(10^11)+1
\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{2015.2016}+\frac{1}{2016.2017}\)
\(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{2016\cdot2017}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2016}-\frac{1}{2017}\)
\(=1-\frac{1}{2017}=\frac{2016}{2017}\)