(X+1)(X+3)分之2+(X+3)(X+5)分之2+(X+5)(X+7)分之2+(X+7)(X+9)分之2的值是多少
问题描述:
(X+1)(X+3)分之2+(X+3)(X+5)分之2+(X+5)(X+7)分之2+(X+7)(X+9)分之2的值是多少
答
=1/(x+1)-1/(x+3)+1/(x+3)-1/(x+5)+……+1/(x-7)-1/(x+9) =1/(x+1)-1/(x+9) =(x+1)(x+9)分之8