How to simplify v/v+1 x 1/v x v/v-1 = 7/w

gusterguy

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If v/v+1 x 1/v x v/v-1 = 7/w for positive integers v and w, what is the value of w? So I have 3 fractions between multiplied together to equal 7 over w. Do I factor? Where to begin? Can I eliminate for example one of the "v"s in the top and bottom to simplify?

Many thanks!

Jeff
 
gusterguy said:
If v/v+1 x 1/v x v/v-1 = 7/w for positive integers v and w, what is the value of w?
Are you sure you're supposed to "simplify" (from your subject line), rather than solve for the value(s) of w...? :?:

If the former, I'm afraid I'm not sure how to proceed. If the latter, then I will first assume that you mean the following:

. . . . .[ v / (v + 1) ] * [ 1 / v ] * [ v / (v - 1) ] = 7 / w

....rather than the "(v/v) + (1x)(1/v)(xv)/v - 1 = 7/w" that you posted. If this is correct, then, noting first that clearly v cannot equal -1, 0, or 1 (why?), you can multiply the left-hand side to get:

. . . . .v / ( v[sup:114bk7u1]2[/sup:114bk7u1] - 1 ) = 7 / w

. . . . .vw = 7v[sup:114bk7u1]2[/sup:114bk7u1] - 7

. . . . .w = 7v - (7/v)

Since w must be a whole number (or its negative), then 7v - (7/v) must be also. Since v is an integer, then clearly so is 7v. This means that, for w to take on a valid value, 7/v must be a whole number.

What values then can v take on? What are the corresponding values of w?

Eliz.
 
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