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a: \(\dfrac{-8}{31}=\dfrac{-8\cdot101}{31\cdot101}=\dfrac{-808}{3131}\)
\(\dfrac{-789}{3131}=\dfrac{-789}{3131}\)
b: Thiếu phân số thứ hai rồi bạn
c: \(\dfrac{1}{n}=\dfrac{n+1}{n\left(n+1\right)}\)
\(\dfrac{1}{n+1}=\dfrac{n}{n\left(n+1\right)}\)
Bài 2:
a: 2/5=14/35
3/7=15/35
b: -3/4=-9/12
-7/-12=7/12
c: 5/9=60/108
-11/-12=11/12=99/108
d: -4/7=-36/63
8/9=56/63
-10/21=-30/63
Bài 2:
a: 2/5=14/35
3/7=15/35
b: -3/4=-9/12
-7/-12=7/12
c: 5/9=60/108
-11/-12=11/12=99/108
d: -4/7=-36/63
8/9=56/63
-10/21=-30/63
Bài 7:
7.1: I là trung điểm của AB
=>\(AB=2\cdot IA=4\left(cm\right)\)
7.2:
C nằm giữa A và B
=>AC+CB=AB
=>CB=10-8=2(cm)
C là trung điểm của NB
=>NC=CB=2cm
C là trung điểm của NB
=>\(NB=2\cdot NC=2\cdot2=4\left(cm\right)\)
Bài 6:
a: \(\dfrac{4}{5}=\dfrac{4\cdot6}{5\cdot6}=\dfrac{24}{30}\)
\(\dfrac{8}{15}=\dfrac{8\cdot2}{15\cdot2}=\dfrac{16}{30}\)
\(-\dfrac{3}{2}=\dfrac{-3\cdot15}{2\cdot15}=-\dfrac{45}{30}\)
b: \(2=\dfrac{2\cdot45}{45}=\dfrac{90}{45}\)
\(\dfrac{-10}{5}=\dfrac{-10\cdot9}{5\cdot9}=\dfrac{-90}{45}\)
\(\dfrac{7}{-9}=\dfrac{-7}{9}=\dfrac{-7\cdot5}{9\cdot5}=\dfrac{-35}{45}\)
c: \(\dfrac{3}{-2}=\dfrac{-3}{2}=\dfrac{-3\cdot6}{2\cdot6}=\dfrac{-18}{12}\)
\(\dfrac{5}{-6}=\dfrac{-5}{6}=\dfrac{-5\cdot2}{6\cdot2}=\dfrac{-10}{12}\)
\(\dfrac{-6}{4}=\dfrac{-6\cdot3}{4\cdot3}=\dfrac{-18}{12}\)
d: \(-\dfrac{1}{2}=\dfrac{-1\cdot15}{2\cdot15}=\dfrac{-15}{30}\)
\(\dfrac{4}{3}=\dfrac{4\cdot10}{3\cdot10}=\dfrac{40}{30}\)
\(\dfrac{6}{-5}=\dfrac{-6}{5}=\dfrac{-6\cdot6}{5\cdot6}=\dfrac{-36}{30}\)
bài 5:
a: \(\dfrac{3}{4}=\dfrac{9}{12};\dfrac{-3}{12}=\dfrac{-3}{12};\dfrac{-2}{3}=-\dfrac{8}{12};\dfrac{-1}{-6}=\dfrac{1}{6}=\dfrac{2}{12}\)
mà -8<-3<2<9
nên \(-\dfrac{8}{12}< -\dfrac{3}{12}< \dfrac{2}{12}< \dfrac{9}{12}\)
=>\(\dfrac{-2}{3}< \dfrac{-3}{12}< \dfrac{-1}{-6}< \dfrac{3}{4}\)
b: Ta có: \(\dfrac{-7}{9}=\dfrac{-28}{36};\dfrac{-1}{3}=\dfrac{-12}{36};-1=-\dfrac{36}{36}\)
mà -36<-28<-12
nên \(-1< -\dfrac{28}{36}< -\dfrac{12}{36}\)
=>\(-1< \dfrac{-7}{9}< -\dfrac{1}{3}< 0\)
\(\dfrac{5}{12}=\dfrac{15}{36};\dfrac{-1}{-4}=\dfrac{1}{4}=\dfrac{9}{36}\)
mà 9<15
nên \(0< \dfrac{1}{4}< \dfrac{5}{12}\)
=>\(-1< -\dfrac{7}{9}< -\dfrac{1}{3}< 0< \dfrac{1}{4}< \dfrac{5}{12}\)
c: \(\dfrac{-1}{-2};0;\dfrac{3}{10};1;\dfrac{-2}{-5};\dfrac{3}{-4}\)
\(-\dfrac{3}{4}< 0\)
\(\dfrac{-1}{-2}=\dfrac{1}{2}=\dfrac{5}{10};\dfrac{3}{10}=\dfrac{3}{10};1=\dfrac{10}{10};\dfrac{-2}{-5}=\dfrac{4}{10}\)
mà 3<4<5<10
nên \(\dfrac{3}{10}< \dfrac{4}{10}< \dfrac{5}{10}< \dfrac{10}{10}\)
=>\(0< \dfrac{3}{10}< \dfrac{-2}{-5}< \dfrac{-1}{-2}< 1\)
=>\(-\dfrac{3}{4}< 0< \dfrac{3}{10}< \dfrac{-2}{-5}< \dfrac{-1}{-2}< 1\)
d: \(-\dfrac{37}{150}=\dfrac{-37}{150};\dfrac{17}{-50}=\dfrac{-17}{50}=\dfrac{-51}{150}\)
\(\dfrac{23}{-25}=\dfrac{-23}{25}=\dfrac{-138}{150};\dfrac{-7}{10}=\dfrac{-105}{150};\dfrac{-2}{5}=-\dfrac{60}{150}\)
mà -138<-105<-60<-51<-37
nên \(-\dfrac{138}{150}< -\dfrac{105}{150}< -\dfrac{60}{150}< -\dfrac{51}{150}< -\dfrac{37}{150}\)
=>\(\dfrac{23}{-25}< \dfrac{-7}{10}< \dfrac{-2}{5}< \dfrac{-17}{50}< \dfrac{37}{-150}\)
a: 5/14=10/28
-3/7=-12/28
-3/4=-21/28
b: 4/11=40/110
-3/5=-66/110
-1/-2=1/2=55/110
c: 7/15=56/120
-3/8=-45/120
-2/3=-80/120
Câu 1:
MSC=60
7/10=7.6/10.6=42/60 5/-12=-5/12=-5.5/12.5=-25/60
Câu 2:
17/34=1/2; -12/22=-6/11; -25/35=-5/7; 125/75=5/3
Câu 3:
MSC=24
1/3=1.8/3.8=8/24 -3/8=-3.3/8.3=-9/24 17/24=17/24
Bài 1:
a. $\frac{4}{5}=\frac{4.4}{5.4}=\frac{16}{20}$
$\frac{3}{-4}=\frac{3.(-5)}{(-4)(-5)}=\frac{-15}{20}$
b.
$5=\frac{5.3}{3}=\frac{15}{3}$
$\frac{1}{3}=\frac{1}{3}$
c.
$\frac{1}{2}=\frac{24}{24.2}=\frac{24}{48}$
$\frac{2}{3}=\frac{2.16}{3.16}=\frac{32}{48}$
$\frac{5}{-16}=\frac{5(-3)}{(-3).(-16)}=\frac{-15}{48}$
Bài 2:
$\frac{7707}{9909}=\frac{7707:1101}{9909:1101}=\frac{7}{9}$
$\frac{22827}{29349}=\frac{22827:3261}{29349:3261}=\frac{7}{9}$
$\frac{29785}{38295}=\frac{297854255}{38295:4255}=\frac{7}{9}$
$\Rightarrow \frac{7707}{9909}=\frac{22827}{29349}=\frac{29785}{38295}$