分母有理化
a=√5+2
b=√5-2
所以ab==5-4=1
a+b=2√5
平方
a²+b²+2ab=20
a²+b²=20-2=18
所以原式=√(18+7)=5
已知a=根号5-2分之1,b=根号5+2分之1,则根号a的平方+b的平方+7的值为多少
已知a=根号5-2分之1,b=根号5+2分之1,则根号a的平方+b的平方+7的值为多少
数学人气:468 ℃时间:2019-08-21 03:59:08
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