Page 216 - Maths Skills - 8

214 Maths

To plot the graph of this situation, we name the coordinates
A(0, 0); B(1, 4); C(2, 8); D(3, 12) and E(4, 16),

We may summarize the rules to plot a graph as follows:
⇒ Write the relation of x and y as a function or an
equation.
⇒ Find the different values of y corresponding to
the values of x.
⇒ Write the values in tabular form.

⇒ Choose a suitable scale on both the axes.
⇒ Plot the points and join them to obtain a graph.
⇒ Label the x-axis and y-axis with the suitable
variables.

Let’s Attempt

Example 1: Draw the graph representing the multiples of 3.
Solution: The equation for representing the multiples of 3 will be y = 3x, where x is any natural number.
If x = 0 ⇒ y = 3 × 0 = 0 The graph will be as shown below.

x = 1 ⇒ y = 3 × 1 = 3
x = 2 ⇒ y = 3 × 2 = 6
x = 3 ⇒ y = 3 × 3 = 9
x = 4 ⇒ y = 3 × 4 = 12

x = 5 ⇒ y = 3 × 5 = 15 and so on.
Tabulating the coordinates, we get
x 0 1 2 3 4 5
y 0 3 6 9 12 15

Example 2 : Express the relation of side of a square and area of a square as a function and plot the graph.
Solution: Let the side of the square be ‘x’ and area of the square be ‘y’.
⇒ y = x 2 (Q Area of square = side )
2
If x = 0 ⇒ y = 0 = 0
2
x = 1 ⇒ y = 1 = 1
2
x = 2 ⇒ y = 2 = 4
2
x = 3 ⇒ y = 3 = 9
2
x = 4 ⇒ y = 4 = 16
2
x = 5 ⇒ y = 5 = 25
2