AP EAMCET2009MathematicsApplication of Derivatives
If f:[2,3] R is defined by f(x)=x^3+3 x-2 , then the range f(x) is contained in the interval
Options
- A[1,12]
- B[12,34]
- C[35,50]
- D[-12,12]
Correct answer
B. [12,34]
Step-by-step solution
Given, f(x)=x^3+3 x-2 On differentiating w.r.t. x , we get aligned & f^ (x)=3 x^2+3 & Put f^ (x)=0 3 x^2+3=0 & x^2=-1 & f(x) is either increasing or decreasing. & At x=2, f(2)=2^3+3(2)-2=12 & At x=3, f(3)=3^3+3(3)-2=34 & f(x) [12,34] . aligned