UPSC NDA Math Model Paper 3

Given, Let f:R→R defined by f(x)={

2x;	x>3
x2;	1<x≤3
3x;	x≤1

To find the value of f(-1) + f(2) + f(4), first find the values of f(-1) , f(2) and f(4) and then add it.
To find f(-1), the function is f(x) = 3x
⇒f(-1) = 3(-1) = - 3
To find f(2), the function is f(x)=x2
⇒f(2)=(2)2=4
To find f(4), the function is f(x) = 2x
⇒f(4) = 2(4) = 8.
Now, f(-1) + f(2) + f(4)
= - 3 + 4 + 8
= 9