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jld902 · Sep 9, 2007, 08:41 PM

these questions really shouldn't be this hard, but for some reason I can't solve them. If anyone could try to point me in the right direction or explain them to me, it would be a big help.

1. [(1/x^-2) + (4/x^-1y^-1) + (1/y^-2)]^-1/2

2. -4(2x-1/2x+1)^-3[(2(2x+1) -(2(2x-1) / (2x+1)^2]

the slashes represent fractions. I hope it isn't too hard to understand.

ebaines · Sep 10, 2007, 08:04 AM

First, some clarification - please confirm that the first problem is properly written as follows:

$ [ \frac 1 {x ^ {-2}} + \frac 4 {x ^ {-1} y ^ {-1}} + \frac 1 {y ^ {-2}}] ^ { - \frac 1 2} $

Thanks.

When you solve these, just remember that a number with a negative exponent simply means 1 over that number raised to the positive exponent. Thus:

$ A^{-B} = \frac 1 {A^B} $

and conversely,

$ \frac 1 {A^ {-B}} = A ^ B $