InterviewSolution
 Saved Bookmarks
    				| 1. | 
                                    If f(x) = x2 + 3x then show that ∆f(x) = 2x + 4 | 
                            
| 
                                   
Answer»  f(x) = x2 + 3 x ∆f(x) = f(x + h) – f(x) = (x + h)2 + 3(x + h) – x2 – 3x = x2 + 2xh + h2 + 3x + 3h – x2 – 3x = 2xh + 3h + h2 Put h = 1, ∆f(x) = 2x + 4  | 
                            |