f:R→R is defined as f(x)=x4−6x2+12. The range of f(x) is
(−∞,∞)
[−3,∞)
[3,∞)
[12,∞)
f(x)=x4−6x2+12f(x)=(x2)2−2×x2×3+32+3f(x)=(x2−3)2+3(x2−3)2≥0(x2−3)2+3≥3⇒f(x)≥3 The range of f(x) is [3,∞)
Let f:R→R be defined as f(x)=x4.Choose the correct answer.