Question

函数y等于根号x方加4分之x方加5的最小值

Answer 1

(x^2+5)/√(x^2+4)

=√(x^2+4)+1/√(x^2+4)

令t=√(x^2+4),则t≥2

y=t+1/t单调递增,

t=2时,ymin=5/2