Problem: If
N=5​+1​5​+2​+5​−2​​−3−22​​
then N equals
Answer Choices:
A. 1
B. 22​−1
C. 25​​
D. 25​​
E. None of these
Solution:
A direct calculation shows that
(5​​+15​+2​+5​−2​​)2=2
and
3−22​=2−22​+1=(2​−1)2
Since a radical sign denotes the positive square root,
N=2​−(2​−1)=1.