2007-09-05 06:48:08 · 4 answers · asked by Gucci 2 in Education & Reference ➔ Homework Help
4 = 2 x 2 ... so you need at least 2 x 2 for the LCD...
20 = 5 x 4 = 5 x 2 x 2.... well you already have the two 2's accounted for from the 4 above... but not a 5.... so now you have at least 2 x 2 x 5...
36 = 4 x 9 = 2 x 2 x 3 x 3... well you already have the two 2's accounted for from the 4... but not the two 3's.... so now your LCD is at least 2 x 2 x 5 x 3 x 3...
90 = 9 x 10 = 3 x 3 x 2 x 5 .... these are already accounted for in you list of factors for 36....
so you have for your LCD... 2 x 2 x 5 x 3 x 3 = 180
4 x 45 = 180
20 x 9 = 180
36 x 5 = 180
90 x 2 = 180
Hope this helps!!!
2007-09-05 06:55:07 · answer #1 · answered by blueskies 7 · 0⤊ 0⤋
That's the least common multiple(lcm) of 4, 20, 36 and 90.
Let's do them 2 at a time.
To get the lcm of 2 numbers, a and b,
you compute (a*b)/gcd(a,b),
where (a,b) is the greatest common factor of a and b.
So
lcm(4,20) = 4*20/4 = 4*5 = 20
lcm(20,36) = 20*36/4 = 20*9 = 180.
Finally,
lcm(180,90) = 180*90/90 = 180.
So the lcm of these 4 numbers is 180.
2007-09-05 14:03:04 · answer #2 · answered by steiner1745 7 · 0⤊ 0⤋
2
HEY YOU DUMMIES!!!! Stop Calculating LCM. The question was for LCD Lowest Common Denominator. Not LCM
Why would you thumbs-down the right answer?
2007-09-05 13:52:51 · answer #3 · answered by Andrew Wiggin 4 · 0⤊ 3⤋
2x2x5x3x3 = 180 pm for method if you want
2007-09-05 13:55:36 · answer #4 · answered by 121ace 1 · 0⤊ 0⤋