Question

函数y=（x^2+5)/根号（x^2+4).(x属于R)的最小值是?用不等式方法解.

Answer 1

y=(x^2+5)/√(x^2+4) ={[√(x^2+4)]^2+1}/√(x^2+4) =√(x^2+4)+[1/√(x^2+4)] >=2*{√(x^2+4)*[1/√(x^2+4)]} =2 所以最小值是2