Question

If $f:[2,\infty )\to B$ defined by $f\left(x\right)=x^2-4x+5$ is a bijection, then$B=$

• A. $[0,\infty )$
• B. $[1,\infty )$
• C. $[4,\infty )$
• D. $[5,\infty )$

Answer 1

Answer: (B)

$[1,\infty )$

$f\left(x\right)=x^2-4x+5=(x-2{)}^2+1$

Clearly in $[2,\infty )$ $f$ is bijective and $B=[1,\infty )$