1、求(+1)+(-2)+(+3)+(-4)+...+(+99)+(-100)的简便运算2、1x2x3+2x3x4+3x4x5+...+7x8x9=_____3、计算:1/2+(1/4+3/4)+(1/6+3/6+5/6)+...+(1/98+3/98+...+97/98)
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![1、求(+1)+(-2)+(+3)+(-4)+...+(+99)+(-100)的简便运算2、1x2x3+2x3x4+3x4x5+...+7x8x9=_____3、计算:1/2+(1/4+3/4)+(1/6+3/6+5/6)+...+(1/98+3/98+...+97/98)](/uploads/image/z/66398-14-8.jpg?t=1%E3%80%81%E6%B1%82%28%2B1%29%2B%28-2%29%2B%28%2B3%29%2B%28-4%29%2B...%2B%28%2B99%29%2B%28-100%29%E7%9A%84%E7%AE%80%E4%BE%BF%E8%BF%90%E7%AE%972%E3%80%811x2x3%2B2x3x4%2B3x4x5%2B...%2B7x8x9%3D_____3%E3%80%81%E8%AE%A1%E7%AE%97%EF%BC%9A1%2F2%2B%281%2F4%2B3%2F4%29%2B%281%2F6%2B3%2F6%2B5%2F6%29%2B...%2B%281%2F98%2B3%2F98%2B...%2B97%2F98%EF%BC%89)
1、求(+1)+(-2)+(+3)+(-4)+...+(+99)+(-100)的简便运算2、1x2x3+2x3x4+3x4x5+...+7x8x9=_____3、计算:1/2+(1/4+3/4)+(1/6+3/6+5/6)+...+(1/98+3/98+...+97/98)
1、求(+1)+(-2)+(+3)+(-4)+...+(+99)+(-100)的简便运算
2、1x2x3+2x3x4+3x4x5+...+7x8x9=_____
3、计算:1/2+(1/4+3/4)+(1/6+3/6+5/6)+...+(1/98+3/98+...+97/98)
1、求(+1)+(-2)+(+3)+(-4)+...+(+99)+(-100)的简便运算2、1x2x3+2x3x4+3x4x5+...+7x8x9=_____3、计算:1/2+(1/4+3/4)+(1/6+3/6+5/6)+...+(1/98+3/98+...+97/98)
1、求(+1)+(-2)+(+3)+(-4)+...+(+99)+(-100)
=50*(-1)
=-50
2、1x2x3+2x3x4+3x4x5+...+7x8x9=1260
3、计算:1/2+(1/4+3/4)+(1/6+3/6+5/6)+...+(1/98+3/98+...+97/98)
=1/2+(1/2)*2+(1/2)*3+(1/2)*4+...+(1/2)*48+(1/2)*49
=1/2(1+2+3+4+...+48+49)
=1/2*(1+49)*49/2
=612.5
1、求(+1)+(-2)+(+3)+(-4)+...+(+99)+(-100)=[(+1)+(-2)]+[(+3)+(-4)]+...+[(+99)+(-100)]=-1×50=-50
2、1x2x3+2x3x4+3x4x5+...+7x8x9=_1260____
3、1/2+(1/4+3/4)+(1/6+3/6+5/6)+...+(1/98+3/98+...+97/98)
=(0+1/2)+1+(1+1/2)+2+…… +(24+1/2)
=0.5+1+1.5+……+24.5
=612.5
100/2*【+1-2】=50*-1=-50
原式={1+【﹣2】}+{3+【﹣4】}+……+{(+99)+(-100)}
=﹣1×50
=﹣50