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问题: 初中数学请教了

实数的运算: (1)(2√5+3√2)(2√5-3√2) (2)(√5-1)^2-(√5-1)(√5+1)

解答:

(1)(2√5+3√2)(2√5-3√2)
=(2√5)^2-(3√2)^2
=20-18
=2

(2)(√5-1)^2-(√5-1)(√5+1)
=(√5-1)((√5-1)-(√5+1))
=(√5-1)(√5-1-√5-1)
=(√5-1)(-2)
=-2√5+2