Need help with: Making a Matrix Singular and Finding Determinates
Ok, i have been working on these problems for a bout an hour now and cant seem to find an answer.
Find all possible values of c that will make the matrix singluar
(c-1) -2 -3
(c-1) (c+1) -3
0 0 1
i used the formula (a11)(a22)(a33)-(a11)(a32)(a23)-(a12)(a21)(a33)+(a12)(a31)(a23)+(a13)(a21)(a32)-(a13)(a31)(a22)=0
solved it out to get c^2+2c-3=0
thus my roots are 3 and -1(but thats not the correct answer....)
Let A and B be 3X3 Matrices with det(A)=2 and det(B)=7
i know that for det(AB) you multiply the 2 but i need to find
If the determinate of a 4X4 matrix A is det(A)=9, and the matrix D is obtained from A by adding 3 times the third row to the second, determine det(D).
Any help is greatly appreciated