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How many triplets (x,y,z) are there if xyz = 2012 and x ≤ y ≤ z?

 Apr 1, 2016

Best Answer 

 #7
avatar+118609 
+10

Hi MWizzard :))

 

The questions use the current year!

I am just going to copy Heureka's method   :)

Given that xyz = 2016 and x, y and z are positive integers such that x < y < z, how many possible triples are there?

 

First you need to work out all the prime factors of 2016

 

\(2016=2^5*3^2*7\)

 

You can work out the third one of each trio yourself  :)

 

 

1 122^4   *3^2   *7
2 13 
3 14 
4 16 
5 17 
6 18 
7 19 
8 112 
9 114 
10 116 
11 118 
12 121 
13 1242*2*3*7
14 127 
15 128 
16 1323*3*7
17 136 
18 14216*3=48
19 23 
20 24 
21 23 
22 27 
23 28 
24 29 
25 212 
26 214 
27 216 
28 218 
29 221 
30 224 
31 2289*4=36
32 34 
33 36 
34 37 
35 38 
36 312 
37 314 
38 316 
39 321 
40 32428
41 46 
42 47 
43 48 
44 49 
45 412 
46 414 
47 42124
48 67 
49 68 
50 612 
51 614 
52 61621
53 78 
54 79 
55 712 
56 71618
57 89 
58 812 
59 81418
60 91416   last one
  1214no good
     
     
     

 

There is probably a much faster way.  But if there is no silly omissions that should be right    crying

I found 60 ordered trios

 Apr 5, 2016
 #1
avatar+118609 
+5

Are x,y and z integers?

 

I will assume that they are positive integers

 

2012=2*2*504

so

x=1, y=4, z=504

or

x=2 y=2  z=504

 Apr 1, 2016
 #2
avatar+425 
0

yes. x, y and z are integers.

MWizard2k04  Apr 1, 2016
 #3
avatar+128475 
+5

The divisors of 2012  are  1, 2, 4, 503, 1006, 2012

 

Assuming that x, y and z don't have to be unique [ all different], we have

 

x      y         z

1     1       2012

1     2       1006

1     4         503

2     2         503

 

4 triplets  ???

 

I think that's it   [ could you check this, heureka???.....your always way better at this than I am....!!!]

 

 

 

cool cool cool

 Apr 1, 2016
 #4
avatar+26367 
+10

How many triplets (x,y,z) are there if xyz = 2012 and x ≤ y ≤ z?

 

\(\begin{array}{|c|c|c|c|c|} \hline & x & y & z & x \le y \le z\\ \hline 1 & 1 & 1 & 2012 & \surd \\ 2 & 1 & 2 & 1006 & \surd \\ 3 & 1 & 4 & 503 & \surd \\ 4 & 1 & 503 & 4 & \\ 5 & 1 & 1006 & 2 & \\ 6 & 1 & 2012 & 1 & \\ 7 & 2 & 1 & 1006 & \\ 8 & 2 & 2 & 503 & \surd \\ 9 & 2 & 503 & 2 & \\ 10 & 2 & 1006 & 1 & \\ 11 & 4 & 1 & 503 & \\ 12 & 4 & 503 & 1 & \\ 13 & 503 & 1 & 4 & \\ 14 & 503 & 2 & 2 & \\ 15 & 503 & 4 & 1 & \\ 16 & 1006 & 1 & 2 & \\ 17 & 1006 & 2 & 1 & \\ 18 & 2012 & 1 & 1 & \\ \hline \end{array}\)

 

It's okay CPhill !

 

laugh

 Apr 1, 2016
 #5
avatar+128475 
+5

Thanks, heureka!!!!!....BTW  .....I meant to type "you're" instead of "your"......doh  !!!!!!

 

 

 

cool cool cool

 Apr 1, 2016
 #6
avatar+425 
0

Help me in Math Olympiad!!!

 

The questions use the current year!

 

Given that xyz = 2016 and x, y and z are positive integers such that x < y < z, how many possible triples are there?

 Apr 5, 2016
 #7
avatar+118609 
+10
Best Answer

Hi MWizzard :))

 

The questions use the current year!

I am just going to copy Heureka's method   :)

Given that xyz = 2016 and x, y and z are positive integers such that x < y < z, how many possible triples are there?

 

First you need to work out all the prime factors of 2016

 

\(2016=2^5*3^2*7\)

 

You can work out the third one of each trio yourself  :)

 

 

1 122^4   *3^2   *7
2 13 
3 14 
4 16 
5 17 
6 18 
7 19 
8 112 
9 114 
10 116 
11 118 
12 121 
13 1242*2*3*7
14 127 
15 128 
16 1323*3*7
17 136 
18 14216*3=48
19 23 
20 24 
21 23 
22 27 
23 28 
24 29 
25 212 
26 214 
27 216 
28 218 
29 221 
30 224 
31 2289*4=36
32 34 
33 36 
34 37 
35 38 
36 312 
37 314 
38 316 
39 321 
40 32428
41 46 
42 47 
43 48 
44 49 
45 412 
46 414 
47 42124
48 67 
49 68 
50 612 
51 614 
52 61621
53 78 
54 79 
55 712 
56 71618
57 89 
58 812 
59 81418
60 91416   last one
  1214no good
     
     
     

 

There is probably a much faster way.  But if there is no silly omissions that should be right    crying

I found 60 ordered trios

Melody Apr 5, 2016
 #8
avatar+425 
+10

Used Excel. Found 59 trios.

MWizard2k04  Apr 30, 2016
 #9
avatar+118609 
0

Yes you are right MWizzard, 27 is not a factor of 2016  :)

 Apr 30, 2016

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