函数y=(x^2+8)/(x-1),x>1,求函数最值要清楚的详细过程
沈海平回答:
y=(x2+8)/(x-1)
=[(x-1)^2+2(x-1)+9]/(x-1)
=(x-1)+2+9/(x-1)
≥2√[(x-1)*9/(x-1)]+2
=6+2
=8
当x-1=9/(x-1)时,取等号,即x=4
函数y=(x2+8)/(x-1),(x>1)的最小值为8
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函数y=(x^2+8)/(x-1),x>1,求函数最值要清楚的详细过程
沈海平回答:
y=(x2+8)/(x-1)
=[(x-1)^2+2(x-1)+9]/(x-1)
=(x-1)+2+9/(x-1)
≥2√[(x-1)*9/(x-1)]+2
=6+2
=8
当x-1=9/(x-1)时,取等号,即x=4
函数y=(x2+8)/(x-1),(x>1)的最小值为8