线性代数subspace验证题求解答:(u1,v1)+(u2,v2)=(u1+u2,v1+v2) belongs to W ( because u1+u2 belongs to U and v1+v2 belongs to V );a(u,v)=(au,av) belongs to W ( because au belongs to U and av belongs to V );(u1,v1)+(u2,v2)=(u1+u2,v1+v2)=(u2+u1,v2+v1)=(u2,v2)+(u1,v1)...