矩阵（）是二次型({x)_(1)}^2+4(x)_(1)(x)_(2)+({x)_(2)}^2的矩阵A({x)_(1)}^2+4(x)_(1)(x)_(2)+({x)_(2)}^2B({x)_(1)}^2+4(x)_(1)(x)_(2)+({x)_(2)}^2C({x)_(1)}^2+4(x)_(1)(x)_(2)+({x)_(2)}^2D({x)_(1)}^2+4(x)_(1)(x)_(2)+({x)_(2)}^2

10.对应二次型 ({x)_(1)}^2+4(x)_(1)(x)_(2)+3({x)_(2)}^2 的矩阵为 () .-|||-

例4 判断二次型-|||-((x)_(1),(x)_(2),(x)_(3))=(x)_(1)^2+2(x)_(2)^2+4(x)_(3)^2+2(x)_(1)(

求二次型 ((x)_(1),(x)_(2),(x)_(3))=4({x)_(2)}^2-3({x)_(3)}^2+4(x)_(1)(x)_(2)-4(x)_(1

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

1.二次型f(x_(1),x_(2))=x_(1)^2+4x_(1)x_(2)+3x_(2)^2的矩阵是（）.A. $\left(\begin{matrix}1

[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)

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

二次型f(x_(1),x_(2),x_(3))=x_(1)^2+4x_(2)^2+4x_(3)^2+2lambda x_(1)x_(2)-2x_(1)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