Help me...im stumped hw problem on matrix determinants...

[jinduy]

given that A is a 3x3 matrix and det(A) = -4, find det(A-2A)

i know how to find det(2A), which is -4*2^3 = -32


can anyone at least hint me as to how would you find det(A-2A)?
or is it like det(A-2A) = det(-A) = -det(A)?

thanks

 

[supesman]

hmm, i don't remember but isn't there a formula that'll make det(A-2A) = det(A) - det (2A) ? if that's the case then you've already solved it.

 

[jinduy]

thanks for reply supesman....


hmmm i tried testing out your hypothesis but i dont think it works that way...