28.求一个正交变换化下列二次型成标准形:-|||-(1) =2({x)_(1)}^2+3({x)_(2)}^2+3({x)_(3)}^2+4(x)_(2)(x)_(3) ;-|||-(2) =({x)_(1)}^2+({x)_(3)}^2+2(x)_(1)(x)_(2)-2(x)_(2)(x)_(3)

28.求一个正交变换化下列二次型成标准形:-|||-(1) =2({x)_(1)}^2+3({x)_(2)}^2+3({x)_(3)}^2+4(x)_(2)(x

[题目]求一个正交变换 =(p)_(y), 把二次型f(x1,-|||-_(2),(x)_(3))=2({x)_(1)}^2+3({x)_(2)}^2+3(x)

29.已知二次型 =2({x)_(1)}^2+3({x)_(2)}^2+3({x)_(3)}^2+2a(x)_(2)(x)_(3)(agt 0) 经正交变换 x

已知二次型-|||-((x)_(1),(x)_(2),(x)_(3))=2({x)_(1)}^2+3({x)_(2)}^2+3({x)_(3)}^2+2a(x)

若二次型((x)_(1),(x)_(2),(x)_(3))=2({x)_(1)}^2+4({x)_(2)}^2+a({x)_(3)}^2+2b(x)_(1)(x

若二次型((x)_(1),(x)_(2),(x)_(3))=2({x)_(1)}^2+4({x)_(2)}^2+a({x)_(3)}^2+2b(x)_(1)(x

用正交变换法化二次型 f ( x _ 1 , x _ 2 , x _ 3 ) = 2 x _ 1 ^ 2 + 3 x _ 2 ^ 2 + 3 x _ 3 ^

二次型((x)_(1),(x)_(2),(x)_(3))=2({x)_(2)}^2+3({x)_(3)}^2的秩为_______.二次型的秩为_______.

7.用正交变换化二次型f(x_(1),x_(2),x_(3))=2x_(1)^2+3x_(2)^2+3x_(3)^2+4x_(2)x_(3)为标准形并写出所用的

例：求一个正交变换x=Py，把二次型f=-2x_(1)x_(2)+2x_(1)x_(3)+2x_(2)x_(3)化为标准形.例：求一个正交变换$x=Py$，把二