Question 82756
changing all the denominators to a-b (-(b-a)) gives


1/(a-b)-2/(a-b)+3/(a-b)-4/(a-b)+5/(a-b)-6/(a-b)+7/(a-b)-8/(a-b)=?/(a-b) ... multiplying by a-b gives


1-2+3-4+5-6+7-8=? ... -4=?