用正交变换将下列实二次型化为标准形i.f(x1,x2,x3)=11x12+5x22+2x32+16x1x2+4x1x3-20x2x3ii.f(x1

用正交变换将下列实二次型化为标准形i.f(x1,x2,x3)=11x12+5x22+2x32+16x1x2+4x1x3-20x2x3ii.f(x1,x2,x3)=x12+x22+x32+4x1x2+4x2x3.