1/1X3+1/3X5···+1/33X35
1个回答
裂项:因为1/n(n+2)=2[1/n-1/(n+2)]
所以 2(1/1-1/3+1/3-1/5+.1/33-1/35)
=2(1-1/35)
相关问题
计算:1/1x3+1/3x5+1/5x7+.+1/31x33+1/33x35,
x1+5x2-x3-x4=-1x1-2x2+x3+3x4=33x1+8x2-x3+x4=1
1*3/1+3*5/1+5*7/1+'''+31*33/1+33*35/1=?
1/3X1/5=1/15=(1/3-1/5)X1/2,1/5X1/7=1/35=(1/5-1/7)X1/2,1/7X1/
{2X1-X2+3X3=33X1+X2-5X3=04X1-X2+X3=3X1+3X2-13X3=-6{X1-2X2+3X
40x=35*(x=4) 7:5=(1/2x):(1/2-42) 3:5=x:(20-x) 1.5x=1.25*(x+1
解方程(1)3(x+6)=9-5(1-2x)(2)[2x+1/5=x+35−1
解方程.(1)6X-35=13 (2)50%X-33%X=34 (3)4.2:1.68=100:
求简便计算:3.51X49+35.1X5.1+49X5.1
4/5x-35=(1+3/20)x