已知,a²-3a+1=0,则求2a²-5a-2-3/(1+a²)的值
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已知,a²-3a+1=0,则求2a²-5a-2-3/(1+a²)的值
已知,a²-3a+1=0,则求2a²-5a-2-3/(1+a²)的值
已知,a²-3a+1=0,则求2a²-5a-2-3/(1+a²)的值
∵a²-3a+1=0
∴2a²-6a+2=0
∴2a²-5a=a-2
∵a²-3a+1=0
∴a²+1=3a
2a²-5a-2-3/(1+a²)
=a-2-2+3/3a
=a-4+1/a
=(a²+1-4a)/a
=(3a-4a)/a
=-a/a
=-1
不懂追问~
a²-3a+1=0,则2a²-6a+2=0,1+a²=3a
2a²-5a-2-3/(1+a²)
=2a²-6a+2+a-4-3/(1+a²)
=(2a²-6a+2)+a-4-3/(1+a²)
=a-4-3/(3a)
=a-4-1/a
=(a²-4a-1)/a
=(a²-3a+1-a-2)/a
=(-a-2)/a
=-1-2/a