已知a,b互为相反数,c,b互为倒数,若a不等于0,求3a+3b+b/a+1/2cd的值还有一个是计算（1/50-1)(1/49-1)(1/48-1)...(1/4-1)(1/3-1)(1/2-1)括号中是(几分之几）减一

b/2d-1

a，b互为相反数，c,b互为倒数，若a不等于0
则a+b=0，cd=1
则b/a=-1
3a+3b+b/a+1/2cd
=3(a+b)-1+1/2*1
=0-1+1/2
=-1/2
（1/50-1)(1/49-1)(1/48-1)...(1/4-1)(1/3-1)(1/2-1)
=49/50*48/49*47/48*……*3/4*2/3*1/2
=1/50

已知a,b互为相反数,则a+b=0
c,b互为倒数,则cd=1
若a不等于0 b=-a b/a=-1
所以3a+3b+b/a+1/2cd
=3(a+b)+(b/a)+(1/2)cd
=3*0+(-1)+(1/2)*1
=-1+1/2
=-1/2
（1/50-1)(1/49-1)(1/48-1)...(1/4-1)(1/3-1)(1/2-1)
=(-49/50)(-48/49)(-47/48).(-3/4)(-2/3)(-1/2)
=-1/50