Wednesday

July 30, 2014

July 30, 2014

Posted by **Angie** on Sunday, March 22, 2009 at 4:06pm.

and write an equation in slope intercept form, without first writing an equation in point-slope form, and then rewriting it to slope-intercept form?

- Math -
**Reiny**, Sunday, March 22, 2009 at 4:18pmsure, first find the slope

slope = (-8+2)/(9-4) = -6/5

then the equation is y = (-6/5)x + b

sub in (4,-2) , or the other point

-2 = (-6/5)(4) + b

I would now multiply by 5 (since I try to avoid fractions as much as possible)

-10 = -24 + 5b

b = 14/5

so y = (-6/5)x + 14/5

- Math -
**GanonTEK**, Sunday, March 22, 2009 at 4:19pmNo, you have to first use

y - y1 = m(x - x1) [point slope form]

and then rewrite in the form

y = mx + c [slope intercept form]

When you are given 2 points you have to find the slope first

[m = (y2 - y1)/(x2 - x1)]

then sub in the slope with either of the points in the equation in point slope form.

Hope that helps.

- Math -
**GanonTEK**, Sunday, March 22, 2009 at 4:21pmI'll correct myself, yes you can I didn't think of the above method by Reiny.

I never used that way before :)

It's quite useful though.

Sorry for my error

- Math -
**Angie**, Sunday, March 22, 2009 at 5:34pmwhy do you have to sub in (4,-2)? why can't you use 9,-8)?

- Math -
**Reiny**, Sunday, March 22, 2009 at 5:40pmAs I said, you can use either point.

I usually use the point that has the "nicer" numbers. Either point will give you the same value of b

A good idea is to then use the other point to see if the equation works.

**Related Questions**

math - i have more than one question so if u no any of the answers please tell ...

Algebra - Choose 1 set of points from the choices below. Then, solve the problem...

Math - Part 1: When writing linear equations, how do you determine which form of...

Algebra - I have an assignment to write an equation to point-slope form, then to...

Algebra - I have an assignment that asks me to write an equation in slope-...

Quick math help - My math exam is coming up Friday and I need help!! Can you ...

math - What happens to y as x gets larger? What happens to x as y gets larger? d...

Math-Algebra 1 - Part 1: When writing linear equations, how do you determine ...

MATH - Solve by finding y and graph using the slope and y-intercept: 3x-y=1 x-y=...

algebra[please check] - in questions 1 and 2, write an equation of the line in ...