Answers

2014-05-18T20:04:29+05:30
Rationalise numerator & denominator we get
lim         (a²-b²){(√x²+c²) + (√x²+d²)} ÷ (c²-d²){(√x²+a²) + (√x²+b²)}
x------>∞
(a²-b²)/(c²-d²) lim           {(√1+c²/x²) + (√1+d²/x²)} ÷ {(√1+a²/x²) + (√1+b²/x²)}
                  x------->∞
= (a²-b²)/(c²-d²) {(1+1)/(1+1)}                    (a²/x² = a²/∞² = 0 & so on for b,c,d)
= (a²-b²)/(c²-d²)
hence (A) option is correct
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