so my problem is 1/8k + 1/5k -1/4k = 3/20
My teacher said to find the LCD out of all the denominators.... would it be 40 or 40k because i tried solving it for both ways and I couldn't get the answer... so maybe the LCD is something different. can you help me?
2007-07-01 04:44:49 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
I don't understand what your teacher meant by LCD, but he's the easy way to do it.
Multiply both sides by 40k or I assume LCD.
1/8k + 1/5k - 1/4k= 3/20
5 + 8 - 10 = 6k
3=6k
k=1/2
2007-07-01 04:55:45 · answer #1 · answered by UnknownD 6 · 0⤊ 0⤋
the LCD would be just 40 because k is part of each of the fractions and is eliminated. if you make a factor tree for each denominator it looks like this:
8k 5k 4k
2*4*k 5*1*k 2*2*k
2*2*2*k
Then you eliminate what is the same for the denominators which is k, one 2 from the 8k and one 2 from the 4k (because let's say k was a 3 if 3 was in place of k it would be in all three denominators there fore 3/3 is equal to 1 therefore eliminating it)
Then you multiply what is left, which is all the other numbers:
2*2*5*1*2 = 40 then you solve
5/40 + 8/40 + 10/40 = 23/40
That is if k is part of the denominator but if it is written as outside the fraction then it would be part of the answer.
2007-07-01 12:11:44 · answer #2 · answered by Anonymous · 0⤊ 0⤋
5 / 40k + 8 / 40k - 10 / 40k = 6 / 40
3 / 40k = 6 / 40
120 = 240k
k = 1 / 2
2007-07-04 17:28:03 · answer #3 · answered by Como 7 · 0⤊ 0⤋