- Thread starter BK94
- Start date

- Joined
- Oct 6, 2005

- Messages
- 10,251

x-intercepts are points that take this form: (x, 0).

I mean, all x-intercepts occur where y = 0.

Substitute 0 for y in your equation, and solve for x.

---------------------------------------------------------

y-intercepts are points that take this form: (0, y).

I mean, all y-intercepts occur where x = 0.

Substitute 0 for x in your equation, and solve for y.

Alternatively, you could recognize that the given equation is written in the Slope-Intercept form of a line. You can see the y-intercept, by inspection.

- Joined
- Oct 6, 2005

- Messages
- 10,251

The instruction "substitute 0 for x in the equation" means to write this:

y = 2(0) + 4

Now, do the math.

y = 0 + 4

y = 4

The y-intercept is 4.

That means the line passes through the point (0, 4).

-------------------------------------------------------------------------

Likewise, the x-intercept is the point where the line crosses the x-axis. The y-coordinate is zero, there. We substitute zero for y.

0 = 2x + 4

Solve for x means to get x by itself on one side.

Subtract 4 from both sides, to first isolate the term containing x.

0 - 4 = 2x + 4 - 4

Do the math.

-4 = 2x

Isolate x by dividing both sides by 2

-4/2 = 2x/2

Do the math

-2 = x

The x-intercept is -2.

That means the line passes through the point (-2, 0).