Question

y=3x²-2ax+a²-1,x>a,求y≥1时,

设a＞0,函数f（x）=3x²-2ax+a²-a.（1）若f（0）≥1,求a的取值范围

Answer 1

f(0)=a²-a≥1
a²-a-1≥0
a≥(1+√5)/2或a≤(1-√5)/2
又因为a>0
所以a的取值范围是a≥(1+√5)/2