0.78*4/13+(11又18/29-2/51)*(0.8-4/5)等於多少

0.78*4/13+(11又18/29-2/51)*(0.8-4/5)等於多少


0.78*4/13+(11又18/29-2/51)*(0.8-4/5)
=39/50×4/13+0
=6/25



1/1*1/3+1/3*1/5+1/5*1/7+.1/49*1/51等於多少,


1/1*1/3+1/3*1/5+1/5*1/7+.+1/49*1/51+…+1/(2n-1)(2n+1)=1/2[1/1-1/3+1/3-1/5+1/5-1/7+.+1/49-1/51+…+1/(2n-1)-1/(2n+1)]=1/2[1-1/(2n+1)]=n/(2n+1)當n=25時,1/1*1/3+1/3*1/5+1/5*1/7+.+1/49*1/51+…+1/(2n-1)(…



(-15)除(-6/25)乘6等於多少


(-15)除(-6/25)乘6等於(-15)乘以(-6/25)乘6=108/5