E-Store
let f(x)=x^3+ax^2+bx+5 sin^2x be an increasing function in the set of real numbers R.then a and b sa
|
| Forum Index -> Differential Calculus -> View Full Question |
|
| Author | Message | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Since f(x) is an increasing function : f '(x) > 0
f '(x) = 3x2 + 2ax + b + 10sinx.cosx = 3x2 + 2ax + b + 5sin2x > 0
As we know : 5 > 5sin2x
3x2 + 2ax + b + 5 > 3x2 + 2ax + b + 5sin2x > 0
3x2 + 2ax + b + 5 > 0
Its discriminant should be less than 0 : (2a)2 - 4(3)(b+5) > 0
a2 - 3b - 15 > 0
|
|||||||||||||
Bipin Kumar Dubey Chemical Dept. IIT Kharagpur |
||||||||||||||
| Like 0 people liked this | ||||||||||||||
|
|
||||||||||||||
Free Sign Up!
Preparing for IIT-JEE ?
Arihant Revision Package for IIT JEE - Books, Practice Tests + Rank Predictor
@ INR 1,995/-
For Quick Info
|
|
|
|
|
| 35,229,755 Engineering Questions Attempted |
6,69,530 Visitors Monthly |
79 Engg. Exam Covered |
647 Students Currently Online |
Connect with Us  |
 |
Vriti Communities
Privacy Policy © Vriti 2011