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GRE Prep Club Team Member
Joined: 20 Feb 2017
Posts: 2506
Given Kudos: 1055
GPA: 3.39
If ab = x and a/b = y, and ab does not equal zero, then
[#permalink]
24 Aug 2021, 05:24
24 Aug 2021, 05:24
Expert Reply
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Question Stats:
60% (02:29) correct
40% (02:33) wrong based on 15 sessions
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If \(ab = x\) and \(\frac{a}{b} = y\), and \(ab\) does not equal zero, then \(a^2 - b^2 =\)
A. \(\frac{x(y - 1)(y + 1)}{y}\)
B. \(xy - \frac{y}{x}\)
C. \(x^2 - y^2\)
D. \(y(x^2 - \frac{1}{x^2})\)
E. \(\frac{(y + x)(y - x)}{x}\)
A. \(\frac{x(y - 1)(y + 1)}{y}\)
B. \(xy - \frac{y}{x}\)
C. \(x^2 - y^2\)
D. \(y(x^2 - \frac{1}{x^2})\)
E. \(\frac{(y + x)(y - x)}{x}\)
Re: If ab = x and a/b = y, and ab does not equal zero, then
[#permalink]
27 Aug 2021, 10:16
27 Aug 2021, 10:16
Expert Reply
ab = x and a/b = y, and ab does not equal zero, then a^2 - b^2 =
a=x/b and a=by
x/b=by
x/y=b^2
since a = by
a^2=(b^2)(y^2)
So a^2-b^2 = (b^2)(y^2)-(x/y)
Since b^2=x/y
=(xy^2)/y-(x/y)
=x(y^2-1)/y
=x(y-1)(y+1)/y
A is the answer
a=x/b and a=by
x/b=by
x/y=b^2
since a = by
a^2=(b^2)(y^2)
So a^2-b^2 = (b^2)(y^2)-(x/y)
Since b^2=x/y
=(xy^2)/y-(x/y)
=x(y^2-1)/y
=x(y-1)(y+1)/y
A is the answer
gmatclubot
Re: If ab = x and a/b = y, and ab does not equal zero, then [#permalink]
27 Aug 2021, 10:16
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