If s is the product of the integers from 100 to 200, inclusive, and t is the product of the integers from 100 to 201, inclusive, what is ~$\frac{1}{s}+\frac{1}{t}$~ in terms of t?
~$\frac{201^{2}}{t}$~
~$\frac{201\times 202}{t}$~
~$\frac{201}{t}$~
~$\frac{202}{t}$~
~$\frac{201\times 202}{t^{2}}$~
哎 把B选项分母的t看成了s, 选了这个
t=100*101*.....*200*201
s= t/201
--> 1/s +1/t = 1/ (t/201) + 1/t= 201/t+ 1/t = 202/t