1／1×3＋1／3×5＋1／5×7······﹢1／47×49

1×2＋3×4+5×6+7×8······+199×200= 1+3+5+···45+47+49+50+51+53+55+···+95+97+99-2-4-6-···-96-98-1 1+1/1+2+1/1+2+3······+1/1+2+3+4+5+6······+46+47+48+49+50得多少? 计算:1/1·5+1/3·7+1/5·9+···+1/21·25 计算1+(2+3)-(4+5)+(6+7)-(8+9)······-(48+49)+50= 1·2·3·4＋1=5²; 2·3·4·5＋1=11²; 3·4·5·6＋1=19²; 1-3+5-7+9-11······+2009-2011+2013-2015 1-3+5-7+······+97-99= -1-3-5-7-9······-97-99怎么计算 1-3+5-7+······+97-99=? (2+4+6+8+······+100)—(1+3+5+7+······+99)等于几 1乘3分之一+3乘5分之一+5乘7分之一+········+49乘51分之一