Hey,

I have this question thats been bugging me for a few days now.

$\displaystyle 3y-15=2x-8$

Whats the answer if we put it in the eqN of a line?

$\displaystyle 2x-3y+7=0$OR$\displaystyle 2x-3y-7=0$?

Thanks for the help.

-NZF

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- Jul 30th 2006, 03:35 PMNineZeroFiveSimple eqN of a line question
Hey,

I have this question thats been bugging me for a few days now.

$\displaystyle 3y-15=2x-8$

Whats the answer if we put it in the eqN of a line?

$\displaystyle 2x-3y+7=0$**OR**$\displaystyle 2x-3y-7=0$?

Thanks for the help.

-NZF - Jul 30th 2006, 03:40 PMQuickQuote:

Originally Posted by**905**

- Jul 30th 2006, 03:44 PMNineZeroFiveQuote:

Originally Posted by**Quick**

EDIT: Actually it's just part of a question, the only part I don't fully understand.

-NZF - Jul 30th 2006, 03:48 PMQuickQuote:

Originally Posted by**NineZeroFive**

$\displaystyle 3y-15=2x-8$

add 15 to both sides $\displaystyle 3y=2x-8+15$

subtract 2x from both sides: $\displaystyle 3y-2x=7$

voila!

~ $\displaystyle Q\!u\!i\!c\!k$ - Jul 30th 2006, 03:50 PMtopsquarkQuote:

Originally Posted by**NineZeroFive**

$\displaystyle y = \frac{2}{3}x + \frac{7}{3}$ (Slope - Intercept form)

and

$\displaystyle (y - 3) = \frac{2}{3}(x - 1)$ (An example of point-slope form)

and

$\displaystyle \frac{x}{3} - \frac{y}{2} = - \frac{7}{6}$ (I forget what this one is called.)

-Dan - Jul 30th 2006, 03:53 PMNineZeroFiveQuote:

Originally Posted by**Quick**

:confused: - Jul 30th 2006, 03:56 PMQuickQuote:

Originally Posted by**NineZeroFive**

- Jul 30th 2006, 03:57 PMNineZeroFive
Sorry,

I think I made a typo somewhere.

3y-15=2x-8 is the equation you need to put in the standard form.

Is the answer 2x-3y+7=0? (textbook answer) Why? -.-

Why is it NOT 2x-3y-7=0?

-NZF - Jul 30th 2006, 03:57 PMtopsquarkQuote:

Originally Posted by**NineZeroFive**

$\displaystyle 3y - 15 - 3y = 2x - 8 - 3y$

$\displaystyle -15 = 2x - 3y - 8$

$\displaystyle -15 + 15 = 2x - 3y - 8 + 15$

$\displaystyle 0 = 2x - 3y + 7$

-Dan - Jul 30th 2006, 04:01 PMQuickQuote:

Originally Posted by**NineZeroFive**

Quote:

Originally Posted by**NineZeroFive**

although I must say, I've never actually seen standard form equalling zero... - Jul 30th 2006, 04:08 PMtopsquarkQuote:

Originally Posted by**Quick**

$\displaystyle 3x^2y^3 - xy^2 + 12x - 3y + 5 = 0$

In the case for a linear equation the form simply becomes:

$\displaystyle ax + by + c = 0$

I'll admit I don't usually see this form for a line, but considering the expression as a multinomial it would be standard.

-Dan - Jul 30th 2006, 04:09 PMNineZeroFiveQuote:

Originally Posted by**Quick**

Why is it 2x-3y+7=0 and NOT 2x-3y**-7**=0?

hmm..

-NZF - Jul 30th 2006, 04:11 PMtopsquarkQuote:

Originally Posted by**NineZeroFive**

-Dan