Wednesday

August 27, 2014

August 27, 2014

Posted by **kay** on Wednesday, March 13, 2013 at 4:23pm.

- math -
**Steve**, Wednesday, March 13, 2013 at 4:29pmYou can't cross-multiply two fractions. It doesn't mean anything. You cross-multiply when you have an equation with fractions, as in

2/3 = 8/12

Then you multiply the left by thr right-side denominator, and vice-versa:

2*12 = 3*8

24 = 24

It's a handy way of getting rid of fractions. What you are really doing is putting everything all over a common denominator, without keeping it around.

2/3 = 8/12

LCD = 36, so

2*12/3*12 = 8*3/12*3

24/36 = 24/36

and you just toss the 36 away, since it no longer affects anything. If two fractions with the same denominator have equal numerators, then they are equal.

If you just want to multiply fractions, your question about

1/2 * 4/22 = (1*4)/(2*22) = 4/44 = 1/11

or, since 1/2 of 4 is 2,

1/2 * 4/22 = 2/22 = 1/11

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