Numerical Analysis/LU decomposition concept quiz

Choose the best answer for each question:

{The LU decomposition is - The name of an algorithm to solve a linear system. + A matrix decomposition which writes a matrix as the product of a lower triangular matrix and an upper triangular matrix. - The same as a QR decomposition. - None of those
 * type=""}

{Is it true that any matrix can be factorized to LU form without pivoting? - Yes + No
 * type=""}

{If A = LU then, det(a) equals: - -det(L)*det(U) + $$ (l_{11}*l_{22}*...*l_{nn})*(u_{11}*u_{22}*...*u_{nn})$$ - Cannot say anything - None of those
 * type=""}

{The computational cost of the LU decomposition of an $$n\times n$$ matrix is: -O($$ n^2$$) -O($$ n^3$$) +O($$ n^3/3$$) -O($$ n^{1/2}$$)
 * type=""}

{The number of operations to solve Ax=b when we know L, U is +O($$ 2n^2$$) -O($$ n^3$$) -O($$ n$$) -O($$ n^{1/2}$$)
 * type=""}