What is the characteristic equation of (abcd)\begin{pmatrix} a & b \\ c & d \end{pmatrix}(acbd)?
λ2−(a+d)λ+(ad−bc)=0\lambda^2 - (a+d)\lambda + (ad-bc) = 0λ2−(a+d)λ+(ad−bc)=0
λ2+(a+d)λ+(ad−bc)=0\lambda^2 + (a+d)\lambda + (ad-bc) = 0λ2+(a+d)λ+(ad−bc)=0
λ2−(ad−bc)λ+(a+d)=0\lambda^2 - (ad-bc)\lambda + (a+d) = 0λ2−(ad−bc)λ+(a+d)=0
λ2−(a+d)λ−(ad−bc)=0\lambda^2 - (a+d)\lambda - (ad-bc) = 0λ2−(a+d)λ−(ad−bc)=0