Week 13 – Math 10 – Linear equation forms

This week in Math 10, I have chosen to talk about the forms of linear equations.

Linear equations are another term for a relation that forms a straight line. You can read my post on X and Y intercepts to learn more about relations. There are three forms to linear equations with different uses.

  • General form
  • Slope y-intercept form (AKA: slope-intercept, slope-y)
  • Point-slope form

Starting with general form, it is the most simple form of a linear equation. The problem is, it lacks all useful information, but can be used to determine X and Y intercepts, as shown in the earlier blog post. It is written in the form \left ( m\cdot-a\right )x + ay + \left ( b\cdot-a\right ) = 0 where M is the slope of the equation.

General form can be easily converted to slope y-intercept form by subtracting the Y and its coefficient from both sides of the equation (like when solving equations.) Note that if the coefficient was negative, it would be added instead.

\left ( m\cdot-a\right )x + \left ( b\cdot-a\right ) = -ay

Dividing everything by -a we convert to slope y-intercept form.

mx + b = y

Slope y-intercept form is called as such because it contains the slope and y coordinate of the y-intercept of the line (the letter b representing the y-intercept coordinate.)

It is impossible to convert from either of the above forms to point-slope form, but point-slope form can be converted to slope y-intercept form, then to general form. It is written with the slope of the line and a single point.

m(x-a)=y-b where A and B represent the X and Y coordinates respectively of the point used in the equation.

To convert to slope y-intercept form, M is distributed to (x+a) and B is moved to the X side the same equation solving method.

mx+\left ( m\cdot a\right )+b=y

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