1.已知x2+y2+z2-2x+4y-6z+14=0,求x+y+z的值.2.当3a2+ab-2b2=0(a≠0,且b≠0)时,求a/b-b/a-(a2+b2)/ab的值.3.(1)已知x+y=10,x3+y3=100,求x2+y2的值;(2)已知a-b=3,求a3-b3-9ab的值.
问题描述:
1.已知x2+y2+z2-2x+4y-6z+14=0,求x+y+z的值.
2.当3a2+ab-2b2=0(a≠0,且b≠0)时,求a/b-b/a-(a2+b2)/ab的值.
3.(1)已知x+y=10,x3+y3=100,求x2+y2的值;
(2)已知a-b=3,求a3-b3-9ab的值.
答
1.(x-1)^2+(y+2)^2+(z-3)^2=0则x=1,y=-2,z=3x+y+z=22.(3a-2b)(a+b)=0则a=-b或a=2/3×b则a/b-b/a-(a^2+b^2)/ab=(a^2-b^2)/ab-(a^2+b^2)/ab=-2b^2/ab=-2b/a若a=-b,则-2b/a=2若a=2/3×b,则-2b/a=-3...