|a|=4,|b|=5,且|a+b|=|a|+|b|,求a+b的值 急,

2025-06-24 05:48:49
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回答1:

|a|=4,|b|=5有四种可能:1、a = 4,b = 5,此时|a+b| = 9,|a|+|b| = 9,满足题意,所以a+b = 92、a = -4,b = -5,此时|a+b| = 9,|a|+|b| = 9,满足题意,所以a+b = -93、a = 4,b = -5,此时|a+b| = 1,|a|+|b| = 9,不满足题意...