已知:a²+a-1=0,求a的三次方+2a²+1999的值
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![已知:a²+a-1=0,求a的三次方+2a²+1999的值](/uploads/image/z/2487536-8-6.jpg?t=%E5%B7%B2%E7%9F%A5%3Aa%26%23178%3B%2Ba-1%3D0%2C%E6%B1%82a%E7%9A%84%E4%B8%89%E6%AC%A1%E6%96%B9%2B2a%26%23178%3B%2B1999%E7%9A%84%E5%80%BC)
已知:a²+a-1=0,求a的三次方+2a²+1999的值
已知:a²+a-1=0,求a的三次方+2a²+1999的值
已知:a²+a-1=0,求a的三次方+2a²+1999的值
∵a²+a-1=0
∴a(a²+a-1)=0 即a³+a²-a=0
又a³+2a²+1999
=a³+a²-a+a²+a-1+2000
=0+0+2000
=2000
a³+2a²+1999
=a(a²+a)+a²+1999
=a+a²+1999
=2000