1.计算 (-47.65)*2又6/11+(-37.15)*(-2又6/11)+10.5*(-1又5*11) 2.已知|x|=1,|y|=2,|z|=3,且xy0.试求(x+y+z)·(xy+yz)的值

来源:学生作业帮助网 编辑:作业帮 时间:2024/05/05 21:24:35
1.计算 (-47.65)*2又6/11+(-37.15)*(-2又6/11)+10.5*(-1又5*11) 2.已知|x|=1,|y|=2,|z|=3,且xy0.试求(x+y+z)·(xy+yz)的值

1.计算 (-47.65)*2又6/11+(-37.15)*(-2又6/11)+10.5*(-1又5*11) 2.已知|x|=1,|y|=2,|z|=3,且xy0.试求(x+y+z)·(xy+yz)的值
1.计算 (-47.65)*2又6/11+(-37.15)*(-2又6/11)+10.5*(-1又5*11)
2.已知|x|=1,|y|=2,|z|=3,且xy0.试求(x+y+z)·(xy+yz)的值

1.计算 (-47.65)*2又6/11+(-37.15)*(-2又6/11)+10.5*(-1又5*11) 2.已知|x|=1,|y|=2,|z|=3,且xy0.试求(x+y+z)·(xy+yz)的值
1.原式=-953/20 * 28/11 + 743/20 * 28/11 - 21/2 * 16/11
=28/11(-953/20+743/20) - 21/2 * 16/11
=-28/11 * 21/2 - 21/2 * 16/11
=21/2(-28/11-16/11)
=-21/2 * 12/11
=-126/11
2.xy0,所以x<0,y>0,z<0
所以 x=-1,y=2,z=-3
所以(x+y+z)·(xy+yz)=(-1+2-3)(-2-6)=(-2)(-8)=16