Show with proof which of these two values is smaller:
7, or √2+√5+√11
I know this problem could be solved using numerous different methods but I am going to post my solution anyway, since I think and I believe I have done a great job in proving it using the most elementary method and the best of observation and thus it earned a place at this blog. :D
My solution:
Observe that
288<289⟹2(122)<172 or (√2<1712)−−−(1)
80<81⟹5(42)<92 or (√5<94)−−−(2)
99<100⟹11(32)<102 or (√11<103)−−−(3)
Adding the inequalities in (2), (2) and (3) up gives us the answer:
√2+√5+√11<1712+94+103=7
Therefore, √2+√5+√11 is smaller than 7.
No comments:
Post a Comment