1/1×3+1/3×5+1/5×7+.......+1/31×33+1/33×35=?
大家帮个忙,能解的!
1/1×3+1/3×5+1/5×7+.......+1/31×33+1/33×35=?
大家帮个忙,能解的!
1/1*3=1/2*(1-1/3)
1/3*5=1/2*(1/3-1/5)
1/1×3+1/3×5+1/5×7+.......+1/31×33+1/33×35=1/2*(1-1/3)+1/2*(1/3-1/5)+1/2*(1/5-1/7)+.......+1/2*(1/31-1/33)+1/2*(1/33-1/35)=1/2*[(1-1/3)+(1/3-1/5)+(1/5-1/7)+.......+(1/31-1/33)+(1/33-1/35)]=1/2*(1-1/35)=1/2*(34/35)=34/70=17/35
1/1×3+1/3×5+1/5×7+.......+1/31×33+1/33×35
=(2/1×3+2/3×5+2/5×7+.......+2/31×33+2/33×35)/2
=(1-1/3+1/3-1/5+1/5-1/7+........+1/31-1/33+1/33-1/35)/2
=(1-1/35)/2
=17/35
晕了 这都是以前我们初中参加奥数才学到的方法解啊 无语了
答案=17/35
1/1×3+1/3×5+1/5×7+.......+1/31×33+1/33×35
=1/2[1/1-1/3+1/3-1/5+1/5-1/7+.......+1/31-1/35]
=0.5*[1-1/35]
=17/35