## DogLuverSarah2012 2 years ago How can you find the standard form of an equation using 2 given points?

1. geoffb

Calculate your slope and the y intercept.

2. geoffb

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3. geoffb

If A is at $$(x_{A}, y_{A})$$ and B is at $$(x_{B}, y_{B})$$, then slope is $$\large \frac{y_{B} - y_{A}}{x_{B} - x_{A}}$$

4. DogLuverSarah2012

Ok so what do I do once I have the slope?

5. geoffb

Then you use it to find the y-intercept. Remember, the y-intercept is at point $$(0, y_{C})$$

6. geoffb

So, if you used point A, you could use $$\large m = \frac{y_{C} - y_{A}}{0 - x_{A}}$$

7. DogLuverSarah2012

ok so once I have the y-intercept???

8. geoffb

Then put it in the form y = mx + b. m is the slope, and b is the y-intercept.

9. DogLuverSarah2012

Ok,I understand that part but how do i find teh standard form of the equation,my book says it would be Ax +By=C but it doesn texplain how to find the equation using 2 given points.

10. geoffb

Oh, sorry. I missed that part of your post. Standard form is just $$Ax + By = C$$ (like you said). You can get it by rearranging your y = mx + b formula.

11. geoffb

Bring y and mx to the same side, to equal b.

12. DogLuverSarah2012

Ok so I have teh x and y intercepts figured out but how do I find C?

13. geoffb

C is just b (from y = mx + b)

14. DogLuverSarah2012

Ok thank you very much!!!

15. geoffb

You're welcome.