1)8/3+(-5/2)+(+16/3)+(-11/2)+(3/4-2/3-1/6)X12=?

5个回答

  • 1)8/3+(-5/2)+(+16/3)+(-11/2)+(3/4-2/3-1/6)X12

    =(8/3+16/3)-(5/2+11/2)+(3*3-2*4-2)

    =8-8+9-8-2

    =-1

    2)4/9X(-9/14)-(-5/9)X(-9/14)-9/14X(-11/9)

    =-4/14-5/14+11/14

    =2/14

    =1/7

    3)1/5X9+1/9X13+1/13X17+...1/101X105

    =1/4(1/5-1/9)+1/4(1/9-1/13)+1/4(1/13-1/17)+…1/4(1/101-1/105)

    =1/4(1/5-1/9+1/9-1/13...+1/101-1/105)

    =1/4(1/5-1/105)

    =1/21

    4)[(-1/2)的平方+(-1/4)X16+4的平方]X[(-3/2)-3]+441/8+1399/14+1399/14X(-7)+1399/2

    =(1/4-4+16)(-9/2)+441/8+1399/14+1399/14X(-7)+1399/14*7

    =49/4*(-9/2)+441/8+1399/14+0

    =-441/8+441/8+1399/14

    =1399/14

    5)(-1)+(-1)的平方+(-1)的立方+...+(-1)的99次方+(-1)的100次方+1/4+1/28+1/70+...+1/9700

    (因为(-1)+(-1)的平方+...+(-1)的99次方+(-1)的100次方=0 )

    所以:

    原式=1/4+1/28+...+1/9700

    =1/1*4+1/4*7+……+1/97*100

    =1/3(1-1/4+1/4-1/7+...+1/97-1/100)

    =1/3(1-1/100)

    =33/100=0.33