BITSAT2015MathematicsApplication of DerivativesActual
The slope of the tangent to the curve y=e^ x cos x is minimum at x= , 0 a 2 , then the value of is
Options
- A0
- B2
- C3 2
Correct answer
B. 2
Step-by-step solution
Let m be the slope of the tangent to the curve y=e^ x x Then, m= d y d x =e^ x ( x- x) Diff. w.r.t 'x' array r dm dx = e ^ x ( x - x )+ e ^ x (- x - x ) =-2 e ^ x x array and d ² ~m dx ² =-2 e ^ x ( x + x ) Put dm dx =0 x =0 x =0, , 2 Clearly, d ² ~m dx ² >0 for x = Thus, y is minimum at x= . Hence the value of =