# Why do we use line graphs?

**Line graphs**can also be used to compare changes over the same period of time for more than one group. Pie charts are best to

**use**when you are trying to compare parts of a whole. They do not show changes over time. Bar

**graphs**are used to compare things between different groups or to track changes over time.

A.

### What does it mean when there is a straight line on a graph?

mx y = and this

**is the**equation of a**straight line**through the origin. This is why the**graph**of x y 4 =**is a straight line**. By**definition**: A**straight line is a graph**which has a constant gradient m.#### What is the equation of the straight line in the graph?

The general equation of a straight line is y = mx + c, where m is the gradient, and y = c is the value where the line cuts the y-axis. This number c is called the**intercept**on the y-axis. The equation of a straight line with gradient m and**intercept**c on the y-axis is y = mx + c.#### Is a straight vertical line a function?

To use the**vertical line**test, take a ruler or other**straight**edge and draw a**line**parallel to the y-axis for any chosen value of x. If, alternatively, a**vertical line**intersects the graph no more than once, no matter where the**vertical line**is placed, then the graph is the graph of a**function**.#### What does the gradient of the line represent?

Slope (or**Gradient**) We call m the slope or**gradient**of the line. It**represents**the change in y-value per unit change in x-value. For example, consider the line given by the equation y = 2x + 1. Here are some points on the line.

B.

### What does the point on a line of a graph represent?

A

**point**-to-**point graph**, also called a**line graph**, is a pictorial rendition of data in which specific values of a function are plotted as dots on a coordinate plane. Adjacent pairs of dots are connected by straight**lines**. Finally, each adjacent pair of**points**is connected by a solid, straight**line**segment.#### What is the difference between a line graph and a scatter plot?

**Scatter plots**show how much one variable is affected by another.**Line graphs**are like**scatter plots in**that they record individual data values as marks on the**graph**. The**difference**is that a**line**is created connecting each data point together.**In**this way, the local change from point to point can be seen.#### Do you read a graph from left to right?

Let's take a look at a few notes that will help**you**make sure your**graphs are**correct when graphing linear equations. When**reading**the**graph**from**left to right**, the line rises if the slope is positive. When**reading**the**graph**from**left to right**, the line falls if the slope is negative.#### How do you draw a graph?

**How to Draw a Graph**- Draw the x axis. Make a horizontal line on the paper.
- Draw the y axis. Make a vertical line that passes through the origin of the x axis.
- Calculate the values of y for several values of x.
- Mark the ordered pairs on the graph.
- You have created a graph of the function f(x) = 2x.

Updated: 2nd November 2019