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Question : 94 of 125
Marks:
+1,
-0
Solution:
Given :
51+x+51−x,‌,52x+5−2x are in A.P.
‌∴‌‌2.‌=51+x+51−x+52x+5−2x‌⇒a=5.5x+5(5x)−1+(5x)2+(5x)−2‌‌ Let ‌5x=t∴‌‌a=5t+‌+t2+‌‌⇒a=t2+‌+5(t+‌)‌⇒a=(t+‌)2−2+5(t+‌)‌‌ Put ‌t+‌=A‌∴a=A2+5A−2‌‌[‌ add & subtract ‌(‌)2]‌⇒a=[A2+5A−(‌)2]+(‌)2−2‌⇒a=(A−‌)2+‌⇒a≥‌
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