Question 1043307
.
If {{{x^2+y^2=85}}} and xy=5, what is the value of {{{(1/x-1/y)^2}}}?
A) 5
B) 75
C) 80
D) 3 
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<pre>
{{{(1/x-1/y)^2}}} = {{{(x-y)^2/(xy)^2}}} = {{{(x^2 - 2xy + y^2)/(xy)^2}}} = 

     replace {{{x^2 + y^2}}} by 85, and replace xy by 5. You will get

= {{{(85-2*5)/5^2}}} = {{{75/25}}} = 3.

<U>Answer</U>.  3.  Option D).
</pre>

Solved