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8 tháng 12 2015

a) goi hai so la a ; b va a >b

vi UCLN(a,b)=18=>a=18k            ;       b=18q       (trong do UCLN (k,q)=1 va k>q)

=>a+b=162

18k+18q =162

18(k+q)=162

k+q=9

ta co bang sau   

 

k1234
q8765
a18365472
b14412610890

vay ...........

   
    
    

 

29 tháng 10 2016

21453 

52542000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000

542454550212.100000000000000000000000000000000000000000000000000000000000000000000000000000
  
  
29 tháng 6 2016

Các bạn cứu với

29 tháng 6 2016

Bó tay ùibucminhXl nhìu nha!!!!!

28 tháng 3 2018

a) ta có UCLN(a;b).BCNN(a;b)=a.b=120.10=1200

UCLN(a;b)=10 \(\Rightarrow\)\(\left\{{}\begin{matrix}a⋮10\\b⋮10\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}a=10k\\b=10h\end{matrix}\right.\left(k;h\right)=1;k\ge h\)

a.b=1200\(\Leftrightarrow\)10k.10h=1200

nên k.h =1200:100=12

mà (k;h)=1 nên (k;h)=(12;1);(4;3)

nên (a;b)=(120;10);(40;30)

16 tháng 4 2020

Ta có : \(\left[a,b\right]=300\) và \(\left(a,b\right)=15\)\(\Rightarrow ab=\left[a,b\right].\left(a,b\right)=300.15=4500\)

Vì \(\left(a,b\right)=15\Rightarrow\hept{\begin{cases}a⋮15\\b⋮15\end{cases}}\)\(\Rightarrow\hept{\begin{cases}a=15m\\b=15n\\\left(m,n\right)=1\end{cases}}\)

Mà \(ab=4500\)

\(\Rightarrow15m.15n=4500\)

\(\Rightarrow225m.n=4500\)

\(\Rightarrow mn=20\)

Vì \(\left(m,n\right)=1\)nên ta có bảng sau :

m     1          20          4          5

n      20        1            5          4

a      15        300        60        75

b      300       15         75        60

Vậy \(\left(a;b\right)\in\left\{\left(15;300\right);\left(300;15\right);\left(60;75\right);\left(75;60\right)\right\}\)