Rearranging an EquationDate: 05/01/99 at 14:04:22 From: Michael Subject: Rearranging an equation Could you please tell me how to rearrange the following equation? y = (900x)/(2+x) Date: 05/01/99 at 21:01:56 From: Doctor Peterson Subject: Re: Rearranging an equation Hi, Michael. I'll assume you want to solve for x in terms of y. The trick is to think of y as a constant; if you aren't confident with this sort of thing yet, you might try a practice run with y replaced by a number, say 2: 900x 2 = ----- 2 + x How would you solve this for x? Multiply both sides by (2 + x) and you'll get 2(2 + x) = 900x Now you can distribute the 2: 4 + x = 900x Now subtract x from both sides: 4 = 899x Finially, divide by 899: x = 4/899 Let's do the same thing keeping the y in place: 900x y = ----- 2 + x Multiply both sides by (2 + x) and you'll get y(2 + x) = 900x Now you can distribute the y: 2y + yx = 900x Now subtract yx from both sides (this is where it can be hard to remember that y is just a constant, and should be treated like the 900): 2y = (900 - y)x Finially, divide by (900 - y): x = 2y/(900 - y) Now you have x in terms of y. Let's check it: 2y 900 * ------- 900x 900 - y 900 * 2y 1800y ----- = ------------- = --------------- = ----- = y 2 + x 2y 2(900 - y) + 2y 1800 2 + ------- 900 - y Wow - it worked! - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/ |
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