已知函数f(x)=x²+(lga+2)x+lgb满足f(-1)=-2,且对一切x都有f(x)≥2x,求实数a,b的值.
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已知函数f(x)=x²+(lga+2)x+lgb满足f(-1)=-2,且对一切x都有f(x)≥2x,求实数a,b的值.
已知函数f(x)=x²+(lga+2)x+lgb满足f(-1)=-2,且对一切x都有f(x)≥2x,求实数a,b的值.
已知函数f(x)=x²+(lga+2)x+lgb满足f(-1)=-2,且对一切x都有f(x)≥2x,求实数a,b的值.
傻逼群
f(-1)=-2
所以-2=1-lga-2+lgb
lga-lgb=1
a/b=10
对一切实数x,都有f(x)大于等于2x,
所以f(x)-2x=x2+(lga)x+lgb>=0恒成立
所以
(lga)^2-4lgb<=0
(1+lgb)^2-4lgb<=0
(1-lgb)^2<=0
lgb=1
b=10
a=100