1. For the straight line y = -2x + 3, what are:
a) the slope = -2
b) the y-intercept? =3
2. The equation of the straight line shown in the diagram is ( y = (½)x - 2
First find the Slope or Gradient (these are two names for the same thing):
Slope = change in y / change in x = 2/4 = 1/2
So m = ½
Now find the y-intercept:
y-intercept = -2
So b = -2
The general equation of a straight line is y = mx + b
So the given line has equation y = (½)x - 2
3. What is the equation of the following line?
y = 0.75x + 2From the graph we can see m = rise/run = 3/4 = 0.75 and b is the y-intercept, so b = 2
Substitute into y = mx + b
Therefore y = 0.75x + 2
4. The equation of the graph y= -4+2
From the graph we can see m = rise/run = -4/1 = -4 and b is the y-intercept, so b = 2
Substitute into y = mx + b
Therefore y = -4x + 2;
5. For the straight line x = 2y - 3, what are:
a) the slope
b) the y-intercept?
From the graph we can see m = rise/run = -4/1 = -4 and b is the y-intercept, so b = 2
Substitute into y = mx + b
Therefore y = -4x + 2
6. What is the equation of the straight line shown in the diagram is y = -4/3x-4
First find the Slope (also called the Gradient):
Slope = (change in y) / (change in x) = -4/3
Now find the y-intercept:
y-intercept = -4
So b = -4
The general equation of a straight line is y = mx + b
So the given line has equation
y = -4/3x - 4
7. What is the equation of the straight line shown in the diagram?
The straight line passes through ... (-5, 4), (-4, 4), (-3, 4), (-2, 4), (-1, 4), (0, 4), (1, 4), (2, 4), (3, 4), (4, 4), (5, 4) ...
Every point on the line has y coordinate equal to 4
Therefore the equation of the line is y = 4
8. What is the equation of the straight line shown in the diagram? x = -3 The straight line passes through ... (-3, 5), (-3, 4), (-3, 3), (-3, 2), (-3, 1), (-3, 0), (-3, -1),
(-3, -2), (-3, -3), (-3, -4), (-3, -5) ...
Every point on the line has x coordinate equal to -3
So the equation of the line is x = -3
9. What is the equation shown in the diagram? of the straight line y = 3x - 5
First find the Slope (also called the Gradient):
Slope = (change in y) / (change in x) = 6/2 = 3
So m = 3
Now find the y-intercept:
y-intercept = -5
So b = -5
The general equation of a straight line is y = mx + b
So the given line has equation y = 3x - 5
10. What is the equation of the straight line shown in the diagram y = -0.6x + 2.5
First find the Slope (also called the Gradient):
Slope = (change in y) / (change in x) = -3/5 = -0.6
So m = -0.6
Now find the y-intercept:
y-intercept = 2.5
So b = 2.5
The general equation of a straight line is y = mx + b
So the given line has equation y = -0.6x + 2.5