BITSAT2009MathematicsApplication of DerivativesActual
The value of (a ) in order that (f(x)= x- x-a x+b ) decreases for all real values is given by
Options
- A(a 2 )
- Ba ( < 2 )
- C(a 1 )
- D(a < 1 )
Correct answer
A. (a 2 )
Step-by-step solution
We have; (f(x)= x- x-a x+b ) ( f^ (x)= x+ x-a ) ( f ^ ( x ) < 0 ~ ~ x R ) ( ( x+ x) < a ~ ~ x R ) As the max. value of (( x+ x) ) is ( 2 ) The above is possible when (a 2 )