Question

a,A=1-2+3+4-5-6+7+8-9-...+2007+2008-2009-2010

b, \(\frac{1}{5^2}-\frac{1}{5^3}+\frac{1}{5^4}-\frac{1}{5^5}+..-\frac{1}{5^{101}}\).CM<\(\frac{1}{30}\)