# Book Extras: Principles of Algebra 2

### eCourse

Don’t miss these video supplements that walk students through the course in an engaging, visual/auditory way!

• Free Online Graphing Calculators – These calculators can be used instead of a graphing calculator for this course. (It is recommended that college-bound students get a graphing calculator, however, so they are already familiar with using one.)
• Desmos (suggested, due to ease of identifying values and zooming in and out) – Note that you have to press the keyboard symbol in the bottom left to get a keyboard. Press y = and the values y equals, using x to stand for the independent variable. Use ^ to show exponents (use your right arrow to get back from an exponent to a regular value). Click on the graph of the curve itself to see the value at any particular point. Zoom in or out using the plus or minus signs. Add a second equation by clicking underneath where the first is typed and typing another one.
• Math Is Fun – Use ^ to show exponents; use the first line for inputting the first equation, and the second for the second.
• Free Online Matrix Calculators – These calculators can be used to calculate matrices.
• Desmos – Input a new matrix for each matrix. Press A, A^-1, B to find (A^-1)(B).
• Math Is Fun – Note that in order to calculate (A^-1)(B), you have to first press “inv(A)”, and then press the “to A” button in order to store it as Matrix A. Then press the AB button to calculate A times B, which is really (A^-1)(B), as you stored A^-1 as A (A^-1 is another way of saying the inverse of A).
• The Atheist Delusion – Watch free online or order a DVD.

### Corrections

#### Textbook

Page 152
The top equation on the page should be a(a – b) + b(a – b) = a^2 – ab + ba – b^2.

#### Teacher Guide/Solution Manual

Worksheet 1.5, Problem 2
Answer should be approximately 4.376 yds.

Quiz 1, Problem 3d
The question should read “if the momentum is 12?” instead of “if the momentum is 10?” which would leave the solution correct except for all the 10s would be 12s in it. The answer would then be 8, as it is listed as right now. As it is right now, however the answer would be approximately 6.667, found by multiplying 2 by approximately 3.33.

Worksheet 1.6, Problem 3a
The 0.9144 in the solution should be 0.914. The answer should be 3.2822757111.

Worksheet 1.6, Problem 3b
3.28227571116 should be used instead of 3.28083989501; the answer should be 0.00186492938134.

Worksheet 1.6, Problem 3c
The answer should be approximately 6.714; in future printings, the instructions should be updated to say “rounding your answer to the second decimal place this time.” Given the updated instructions, the answer would then be 6.71, which would preserve significant digits (something not gone over in this course, but students who follow it should have their answers counted as correct).

Worksheet 2.7B, Problem 3
The instructions should say, “find the answer if the unknown equals 2” rather than “if a equals 2.”

Quiz 2, Problem 1f
Answer as the problem is should be a^4. Problem should be updated in future printings to be (a^2)^-2, in which case the current solution and answer is correct.

Quiz 2, Problem 1k
Problem should be clarified to be -(2)^2(-3)^2. Solution should be clarified like this: -(2)^2(-3)^2 = (-1)(2^2)(-3)^2 = (-1)(4)(9) = -36.

Quiz 7, Problem 1e
Answer should be r = 0 (all bold).

Quiz 7, Problem 1g
Answer should be (0,0) and the l = 0 should be removed. This note in the sidebar should be added: Found by graphing F(l) = 5l, which gets inputted into the calculator as y = 5x, and looking at the point where the line intercepts the x-axis.

Quiz 10, Problem 2b
As it is right now, the answer of approximately +- sqrt 4/5i should not be listed, as it is complex and the instructions say not to list complex roots. However, students who list it should not be penalized. In future printings, the instructions should be adjusted to include complex roots, and the references to real solutions removed in the solution. If we were just looking for real roots, we could just graph to see the x = 0.