已知a²-3a-1=0,则4+1/a²+a²的值为?市一模上的题有点不懂,
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![已知a²-3a-1=0,则4+1/a²+a²的值为?市一模上的题有点不懂,](/uploads/image/z/3942043-43-3.jpg?t=%E5%B7%B2%E7%9F%A5a%26%23178%3B%EF%BC%8D3a%EF%BC%8D1%EF%BC%9D0%2C%E5%88%994%EF%BC%8B1%EF%BC%8Fa%26%23178%3B%EF%BC%8Ba%26%23178%3B%E7%9A%84%E5%80%BC%E4%B8%BA%3F%E5%B8%82%E4%B8%80%E6%A8%A1%E4%B8%8A%E7%9A%84%E9%A2%98%E6%9C%89%E7%82%B9%E4%B8%8D%E6%87%82%2C)
已知a²-3a-1=0,则4+1/a²+a²的值为?市一模上的题有点不懂,
已知a²-3a-1=0,则4+1/a²+a²的值为?
市一模上的题有点不懂,
已知a²-3a-1=0,则4+1/a²+a²的值为?市一模上的题有点不懂,
a²-3a-1=0
很明显a不等于0,两边同时除以a得:
a-3-1/a=0
a-1/a=3
两边平方得:
a²+1/a²-2=9
a²+1/a²=11
两边同时加上4得:
4+1/a²+a²=15