题目n元齐次线性方程组AX=0有非零解的充分必要条件是()A. r(A) = nB. r(A) > nC. r(A) ≤ nD. r(A) n元齐次线性方程组AX=0有非零解的充分必要条件是()A. r(A) = nB. r(A) > nC. r(A) ≤ nD. r(A) < n题目解答答案D. r(A) < n