Let's review:
- Slope intercept form is y=mx+b
- <em>m </em>is the slope
- <em>b </em>is the y-intercept
First, find the slope.
Remember: It's rise over run! Δy (delta y) over Δx (delta x)! You can use the formula:
y2-y1/x2-x1.
Solve:
The second coordinate is (4,8). The y is 8. The first coordinate is (0,5). The y is 5. So, 8 minus 5 is 3. That's your top portion. The bottom portion is the x coordinates. The second coordinate's x is 4. The first coordinate's x is 0. Subtract...
<em>Let's just put that into a visual thing now...</em>
y2=8 y1=5 x2=4 x1=0
<u>8-5 = 3</u>
4-0 = 4 <em> So your slope is 3/4.</em>
Then, find the y-intercept.
Substitute in the coordinates, and then solve the equation. Let's take what we have now. y=3/4 x+b
Take one of your ordered pairs and substitute it in with that information. So instead of y=3/4 x+b, you can have either 5=3/4(0)+b or 8=3/4(4)+b. Either one works. Let's go with 5=3/4(0)+b.
Solve this equation.
5=3/4(0)+b <em>Now, multiply the 3/4 by the 0.</em>
5=0+b <em>This is the same thing as 5=b</em>
5=b <em>This is the y-intercept. b is 5.</em>
Put the components of your equation all together.
The slope is 3/4. The y-intercept is 5.
<u><em>The answer is:</em></u>
<u><em>y=3/4 x+5</em></u>
Hope that helps!