If x^2 + 9/x^2 = 15, what is the value of x - 3/x
Pick one
A) 36 B) 25 C) 9 D) 5 E) 3
To find : x-3/x. Let it be t.   =&gt; x-3/x = t   =&gt; (x^2 + 9/x^2) - 2*x*3/x = t^2 (Squaring both sides).   =&gt; (15) - 2*3= 
<gadget id="calculator">(15) - 2*3</gadget>
<output>9</output>
9=&gt; t^2 = 9. Thus t=3 or t=-3.   Answer 3
<result>E</result>
If x^2 + 9/x^2 = 15, what is the value of x - 3/x