**Variation in the value of m with the value of c kept constant**

Increase the value of

*m*. What do you observe about the straight line?As

*m*increases, the slope becomes steeper.Now decrease the value of

*m*. What do you observe about the straight line?As

*m*decreases, the slope becomes more gentle.Now further decrease the value of

*m*till it comes negative. What do you observe about the straight line?The line continues to "go down": Now the axis points from top left corner towards bottom right corner. (opposite direction).

Now set the value

*m*= 0. What do you observe about the straight line?When

*m*becomes zero, the line becomes the horizontal line that overlaps with the*x*axis.**Variation in the value of c with the value of m kept constant**

Increase the value of

*c*. What do you observe about the straight line?The straight line 'moves' up, and it remains parallel to the original line.

Now decrease the value of

*c*. What do you observe about the straight line?The straight line 'moves' up, and it remains parallel to the original line.

*c*= 0?

The straight one passes through the origin.

Now summarize on your own the effect of *m*and

*c*on a straight line with equation y =

*m*x +

*c*

*c*is the vertical intercept that tells us where the graph will intersect/ cut the y axis whereas

*m*is the gradient that tells us the orientation of the graph (steep/ gentle, pointing upwards/ downwards).

What happen if now we have two lines having the

**same gradient**?

Consider y = 2x + 4 and y = 2x - 1

What happen if now we have two lines having the same y-intercept?

Consider y = 2x + 1 and y = -4x + 1

The two line will cut the y-axis at y = 1

What is the general form of a horizontal straight line?

Why is it in that particular form?

The general form is y = c when c is the 'y'-intercept

i.e. when the line is parallel to the x axis.

What is the general form of a vertical straight line?

What is it in that particular form?

The general form is x = n where n is the 'x'-intercept

i.e. when the line is parallel to the y axis.

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