Exercise 2.2.21

Answers

(a) Pivots 2, 3 2, 4 3, 5 4 in the equations 2x + y = 0, 3 2y + z = 0, 4 3z + t = 0, 5 4t = 5 after elimination. Back substitution gives t = 4,z = 3,y = 2,x = 1.

(b) If the off-diagonal entries change from + 1 to 1, the pivots are the same. The solution is (1,2,3,4) instead of (1,2,3,4).

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2021-11-20 15:07
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