Lesson video

Hi, I'm Miss Davies.

In this lesson, we're going to be drawing graphs that are in the form y = mx + c.

We are working with graphs that are in the form y = mx + c.

In this, the x and the y values are the coordinates of the points.

The m value is gradient of the line.

This is the steepness of the given line.

For every one unit that it moves to the right, how many units does it move up or down? The c value is the y-intercept.

This is the point in which the line crosses the y-axis.

In which pairs of coordinates is the y value 3 more than double the double the x value? 4, 11.

Negative 9, negative 15.

And 0, 3.

Which of the points lie on the line y = 2x + 3? It is these three points.

We've been asked to complete the table of values for the line y = 2x + 3.

The table of values is completed by substituting in values for x into the equation.

If we substitute in negative 2, we'll be calculating 2 multiplied by negative 2, add 3.

This gives negative 1.

When x is negative 1, we're going to calculate 2 multiplied by negative 1, add 3 to find y, which is 1.

When x is 1, y is 5.

We can then use this to plot the graph of y = 2x + 3.

Using these coordinates to plot each of the points and then joining these up with a straight line.

Notice that this line runs from the edge of the set of axis we've been given, rather than just from the first point to the last point.

Which of these coordinates lie on the line y = -x + 1? Negative 7, 8.

2, negative 1.

And 0, 1.

Next, we're going to complete the table of values for the line y = -x + 1.

We're going to find the y-coordinate when x is equal to negative 1, 0, and 2.

When x is negative 1, y is 2.

And negative -1, add 1, is equal to 2.

When x is 0, y is 1.

When x is 2, y is negative 1.

We're now going to plot this graph.

We're going to use these coordinates to plot the points that we have just worked out.

We can then join these together with a straight line that runs from edge to edge of the grid.

You can see that this line has got a negative gradient and for every one unit it goes to the right, it goes one unit down.

This is because the gradient of the equation is negative 1.

Here is some questions for you to try.

Pause the video to complete your task and resume once your finished.

Here are the answers.

In this graph, the gradient is 2.

This means that for every one unit that it moves to the right, it moves two units up.

Here is some questions for you to try.

Pause the video to complete your task and resume once you're finished.

Here are the answers.

The line P has a gradient of 3.

Line Q has a gradient of negative 1.

And line R has a gradient of a half.

This means that for every two units that line R moves to the right, it moves one up.

That's all for this lesson.

Thanks for watching.