AP EAMCET2011MathematicsApplication of Derivatives
If f:[2, ) B defined by f(x)=x^2-4 x+5 is a bijection, then B is equal to
Options
- A[0, )
- B[1, )
- C[4, )
- D[5, )
Correct answer
B. [1, )
Step-by-step solution
Given, f(x)=x^2-4 x+5 On differentiating w.r.t. x , we get f^ (x)=2 x-4 Put f^ (x)=0 x=2 For x>2, f^ (x)>0 , increasing Minimum value is f(2)=4-8+5=1 B [1, )