A function in which the minimum degree or power of the dependent variable is two is called a non-linear function and its graph will always be a curve. The most basic non-linear function is: y=x2.

Here, x is an independent variable and y is dependent on x. We can also say, y is a function of x, and written in mathematical terms this is y = f(x), so we can write our function as f(x) = x2.

To plot any graph we need to find the set of points or ordered pairs and identify the curve.

X	Y
0	0
1	1
2	4
-1	1
-2	4

In this graph, two different values of x evaluate to the same value. For example f (-2) = f(2) = 4

f (-2) = 4 means that the function evaluated at x=-2 has a value of 4 or y = 4.

Try these questions

1. Identify the graph of (x-3)(2x+5)
   
   
   
   Answer: D


2. 
   
   1. All real numbers.
   2. All negative numbers.
   3. All positive numbers.
   4. None of these.
   Answer: C


3. The range of the function 3x2 + 5; x ≥ - 2 is
   
   1. All real numbers.
   2. All positive numbers ≥ 17
   3. All positive real numbers
   4. None of these.
   Answer: C