集合B={x∈R|x=4t+1/t -6,t∈（0,+∞）},求集合x的取值?

题目

集合B={x∈R|x=4t+1/t -6,t∈（0,+∞）},求集合x的取值?

答案

根据均值不等式:4t+1/t-6>=2*[根号下4t*(1/t)]-6=-2所以x>=-2