Economic Math Review

Common Questions: 

How are my math skills? 

What topics I need to work on? 

How can I get better? 

Complete Pre- Test  http://cstl.syr.edu/fipse/pretests/EconTest/Econ3b.html

Upon completion the number of correct questions are shown on the screen and weak subject areas are indicated; if any. Study weak topics before going to class. Get a head start on your learning.

Math Review Sheet for Economics



Slope of a Line:

If a line passes through two distinct points P₁(x₁ , y₁) and P₂(x₂, y₂), its slope is given by:

m = (y₂ - y₁) / (x₂ - x₁)

with x₂ not equal to x₁.
General Equation of a Straight line:

The general equation of straight line is given by:

Ax + By = C

where A, B and C are constants and A and B cannot be both zero.

Slope intercept form of a Line:
The equation of a line with a defined slope m can also be written as follows: y = mx + b

where m is the slope of the line and b is the y intercept of the graph of the line.
The above form is called the slope intercept form of a line.

Point-Slope form of a line:

An equation of a line through a point P(x₁ , y₁) with slope m is given by

y - y₁ = m(x - x₁)

Vertical and Horizontal lines:

a - If we set A to zero in the general equation, we obtain an equation in y only of the form

By = C

which gives y = C/B = k; k is a constant. This is a horizontal line with slope 0 and passes through all points with y coordinate equal to k.

b - If we set B to zero in the general equation, we obtain

Ax = C

which gives x = C/A = h; h is constant. This is a vertical line with undefined slope and passes through all points with x coordinate equal to h.

Parallel Lines:

Two non vertical lines are parallel if and only if their slopes are equal.

Perpendicular Lines:

Two non vertical lines are perpendicular if and only if their slopes m₁ and m₂ are such that

m₁*m₂ = -1

                                                                  

Math Review Sheet for Economics

Example 1: Find the slope of a line passing through the points

1. (2 , 3) and (0 , -1)
2. (-2 , 4) and (-2 , 6)
3. (5 , 2) and (-7 , 2)

Example 2: Find the equation of the line that passes through the point (-2 , 5) and has a slope of -4.

Example 3: Find the equation of the line that passes through the points (0, -1) and (3, 5).

Exercise 4: Find the slope of a line passing through the points

1. (-2 , 7) and (-2 , -1)
2. (2 , 4) and (-2 , 6)
3. (-1 , -2) and (4 , -2)

Exercise 5: Find the equation of the line that passes through the point 
 (3 , 0) and has a slope of - 1.

Exercise 6: Find the equation of the line that passes through the points (2, 0) and (3 , 3).  

Graphing Video Links:

Market (Supply and Demand)- https://youtu.be/Oq0oM4-WFcI

Supply (Change in Supply VS Change in Quantity Supplied)- https://youtu.be/TOZ-VRVCqzo 

Demand (Change in Demand VS Change in Quantity Demanded)- https://youtu.be/LekDr6grE2c