线性代数,计算题
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线性代数,计算题
按第n列展开
Dn = an (-1)^(1+n) (-x1)(-x2)...(-xn-1) + xnDn-1
= x1x2...xn-1an + xnDn-1 = x1x2...xn-1an + xn( x1x2...xn-2an-1 + xn-1Dn-2 )
= x1x2...xn-1an + x1x2...xn-2an-1xn + xnxn-1Dn-2
= ...(迭代)
= x1x2...xn-1an + x1x2...xn-2an-1xn +...+ x1a2...xn-1xn + xnxn-1...x2D1
= x1x2...xn-1an + x1x2...xn-2an-1xn +...+ x1a2...xn-1xn + a1x2...xn-1xn
Dn = an (-1)^(1+n) (-x1)(-x2)...(-xn-1) + xnDn-1
= x1x2...xn-1an + xnDn-1 = x1x2...xn-1an + xn( x1x2...xn-2an-1 + xn-1Dn-2 )
= x1x2...xn-1an + x1x2...xn-2an-1xn + xnxn-1Dn-2
= ...(迭代)
= x1x2...xn-1an + x1x2...xn-2an-1xn +...+ x1a2...xn-1xn + xnxn-1...x2D1
= x1x2...xn-1an + x1x2...xn-2an-1xn +...+ x1a2...xn-1xn + a1x2...xn-1xn