Algebra/Standard Form and Solving Slope

Algebra

Standard Form

Standard form is another way to write slope (as opposed to y=mx+b). It is written as Ax+By=C. You can also change slope-intercept form to standard form like this: Y=-3/2x+3. Next you have to isolate the y- intercept(in this case it is 3) like this: Add 3/2x to each side of the equation to get this: 3/2x+y=3. You can't have a fraction in standard form so you solve this. 2(3/2x+y)=5(2). To get: 3x+2y= 10. Now you have a standard form equation!

Solving Slope

Solving Standard Form

Slope intercept equations (y=mx+b) are the easiest to graph. So if you encounter an equation in standard form that you are required to graph, you must convert it to slope intercept form. To do this you must take the equation and solve for Y.

Example:

9x + 7y = − 3

9x − 9x + 7y = − 3 − 9x

7y = − 3 − 9x

$\frac{7y}{7}=\frac{-3 - 9x}{7}$

$y = \frac{-3}{7}-\frac{9}{7}x$

That is technically slope intercept form, but if you want to make it true (y=mx+b) simply follow the rule of negatives (a - b = a + -b):

$y = \frac{-9}{7}x+\frac{-3}{7}$

Solving Slope Intercept Form

If you come upon an equation in slope intercept form, and require it to be in standard form, simply solve for m (c).

Example:

y = 10x + 9

y − 10x = 9 + 10x − 10x

y − 10x = 9

Standard form cannot have fractions if they are in a fraction, you must multiply each side to get rid of it.

Example:

$\frac{9}{10}x + 9y = 5$

$10 [\frac{9}{10}x + 9y] = 10 [5]$

9x + 90y = 50