# Feedback Q&A on Algebra

by Ron Kurtus

Readers have sent in a total of 66 comments and questions on Algebra issues. They are listed according to date.

You can read them to further your understanding of the subject.

## List of next 10 letters

### Country

General Do you have DVDs of courses? Somalia

General Correcting error in test USA

General Solve my homework India

Multiplying Binomial Expressions Multiplication problem Philippines

Variables and Constants Following the laws for exponents U.A.E.

Expressions I need help to understand the term sub-expression USA

Linear Equation with One Variable Two exceptions in equations USA

Quadratic Equations Explain how the quadratic formula is derived USA

Division with Exponents How do you do 4 to the negative 5 power? USA

Linear Equation with One Variable Tough algebra problems India

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First 10 letters

## Do you have DVDs of courses?

Topic: General

### Question

January 13, 2011

do you have any course DVDs of mathmatical and science for high school students or other websites which can help for our how we study them as international? thanks you

hassan - Somalia

21015

### Answer

I'm sorry, but we do not have any DVDs on our courses at this time. Your high school students can go through our lessons to help them learn the subjects. Also, each lesson and each subject has a list of resources. For example, a list of other Algebra websites can be seen at:

http://www.school-for-champions.com/algebra/resources.htm

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## Correcting error in test

Topic: General

### Question

November 29, 2010

I noticed an error in your first Algebra test on question 15. The expression listed does not match any of the choices offered. It would seem that the x was placed on the wrong side of the parenthesis.

(excerpt from test)
15. Which of the following is equal to -7x(3 - 2y - z)?

Not Sure

-21x - 14y - 7z

21x + 14y - 7z

-21x + 14y + 7z
(end inclusion)

Brian - USA

20759

### Answer

Thanks for letting me know about it. I corrected the error. It should have been -7(3x - 2y - z)

You might have to refresh the page to verify the question has been updated.

Thanks, again.

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## Solve my homework

Topic: General

### Question

November 16, 2010

1) prove by mean value theorm 3+(1/28)<(28)^(1/3)<3+(1/27).
^ means the power of (28) is 1/3.

2)prove that x-1<1/10 then x^3+1<0.331.
x-1 means in mode x-1.

3)prove by sandwich theorm for sequence that as n tends to infinite x^n=0 and x<1 is given.
please send me the solutions as soon as possible.

rrg - India

20705

### Answer

I'm sorry, but we cannot solve homework problems.

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## Multiplication problem

Topic: Multiplying Binomial Expressions

### Question

June 30, 2010

multiply: [125(a+b)^25][-25(a+b)^20]

Wylbur - Philippines

19987

### Answer

Since the expressions are all multiplied together, they really are not binomial expressions.

Simply multiply:

(125)*(-25) = -3125

[(a+b)^25]*[9a+b)^20] = (a+b)^45

So, the answer is: -3125(a+b)^45. You are not expected to put (a+b)^45 in any other form.

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## Following the laws for exponents

Topic: Variables and Constants

### Question

June 8, 2010

greetings!! I am a grade 6 student studying in the U.A.E. I really want to know algebra more since our school here is so advanced. i just want to ask,,, in algebra, is there a need for the laws of exponents. i mean should we follow the rules??? and please teach me how to solve different kinds of long equations because it is kind of confusing.
I usually fail in math because of problem solvings....

Thanks!!!!

Hannah Grace - U.A.E.

19861

### Answer

There are definite laws or rules for multiplying and dividing exponents. It is good to know those rules, because it makes the activities easier. Otherwise you need to break down the exponent as repeated multiplications, and that can really slow you down.

For the rules, see:
http://www.school-for-champions.com/algebra/exponents_multiplication.htm
and
http://www.school-for-champions.com/algebra/exponents_division.htm

Best wishes for top grades in algebra.

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## I need help to understand the term sub-expression

Topic: Expressions

### Question

February 4, 2010

I need help to understand the term sub-expression. I had never seen that until I came to your web site. I like the immediate interaction questions because it helps me to understand the concepts when I know if my answer is right or not. I found out that you have to be in a peaceful state of mind and have a clear head in order to study algebra. It is not possible to understand it when you have other personal issues going on in your brain.

Ms. M. - USA

19158

### Answer

If you have a complex expression, you can consider parts of it as sub-expressions. For example, the expression 2Y + (3Z + 1) has sub-expressions 2Y and 3Z + 1.

Calling them sub-expressions just allows you to realize that they are expressions within a larger expression. Some Algebra books do not distinguish between expression and sub-expressions.

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## Two exceptions in equations

Topic: Linear Equation with One Variable

### Question

January 6, 2010

It is said that there are 2 exceptions to the rule; What you do on the left side of the equal sign, you must do on the right side. What are those 2 exceptions?

Luis - USA

18982

### Answer

You cannot multiply or divide both sides by zero.

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## Explain how the quadratic formula is derived

Topic: Quadratic Equations

### Question

December 23, 2009

Can you please explain how the quadratic formula is derived from the quadratic equation? Thank you.

Ann - USA

18917

### Answer

See: http://www.school-for-champions.com/algebra/quadratic_formula_derivation.htm

It is a new page that will help answer your question.

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## How do you do 4 to the negative 5 power?

Topic: Division with Exponents

### Question

November 19, 2009

How do you do 4 to the negative 5 power?

- USA

18704

### Answer

A number raised to a negative exponent equals the reciprocal of the number raised to a positive exponent. For example, 4^-5 = 1/4^5.

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## Tough algebra problems

Topic: Linear Equation with One Variable

### Question

September 27, 2009

these are some of my questions i read in class 8th cbse and have to do hard work in this board session so i need some help:-
1.if i add 10 to 4 times anumber, the result is five less than five times the number. what is my number?
2.what are 3 consecutive odd integers.the sum of 1st and last of these integers is 26.what are the integers?
that much some of my queries i'll ask you later as i take time.

Anshul - India

18394

### Answer

Add 10 to 4 times a number = 4x + 10
Result is 5 less than 5 time number = 5x - 5
Thus 4x + 10 = 5x - 5
Subtract 4x from both sides and add 5 to both sides of the equation.
15 = x

The second problem is tricky. 2x is always an even number and 2x + 1 is odd.
Let 2x + 1 = first odd integer, 2x + 3 = second, 2x + 5 = third.
(2x + 1) + (2x + 5) = 26
4x + 6 + 26
4x = 20
x = 5
2x + 1 = 11, 2x + 3 = 13, 2x + 5 = 15.

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## Summary

Hopefully, this reader feedback has helped provide information about Algebra issues.

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