Algebra help for homeschool mom?

Question

my book doesn't have an answer key- but i don't want to rely on that alone, i want to actually understand what i am teaching and it has been a while since i have used this.

the book says the answers with a calculator are the same, using the algebraic method and parentheses. here is the example:

3-4x8+(plus/minus sign on calculator)+7=

7+ (3-4x8) (plus/minus sign on calculator)=

these are for the calculator- when i do it one way, i get negative 1, but the other way i get 15, but the book says they should be the same. help!!

here is the first question as written: i got 2.72

[6.1(3.2)-27.8]+11 they used tall lines instead of brackets

Answer 1

The "tall lines" are called absolute value and they are NOT brackets.

What do you mean by "plus/minus sign on calculator"

Answer 2

Honestly, you might want to look into another curriculum, or find the solutions manual.  I do know where you're coming from - I barely understood algebra the first time around, never mind trying to tackle it 20 years later - so I found a curriculum that teaches my son by DVD.

The ones that do this can be a bit pricey, but you can find them for less at places like eBay and VegSource Homeschool Swap.  Trust me, they are completely worth the money.

The top three that I would recommend are VideoText Interactive, Teaching Textbooks, or Math U See.  I know it's a pain to switch curriculums, but if you don't understand it (like me), you need to have a resource that will teach directly to your child.

It looks like the concepts being taught are order of operations, properties of functions (commutative, associative, distributive), and absolute value.  I'm not quite sure what you mean by (plus/minus sign on the calculator), so I can't really help you there. The tall lines, I believe, are absolute value instead of brackets or parentheses.  

In the first question, is 3-4x8 in parentheses in your book?  If so, yes, it would equal out to negative 1.

I honestly would recommend that you try another curriculum, rather than trying to figure out a book that doesn't come with a solutions manual.

Answer 3

Hi there,

Well I know how you got the 2.72 you went like this:

6.1 * 3.2 -27.8+11 = 2.72

But that might be correct... Scroll down to see...

Remember this when figuring out complex algebraic equations:

Please Excuse My Dear Aunt Sally

P= Parenthises

Excuse = Exponents

My = Mulitplication

Dear = Division

Aunt = Addition

Sally= Subtraction

This is called the order of operations.  In order to get the correct answer you must follow it....

So lets have a look at that equation...

[6.1(3.2)-27.8]+11

First I would do this:

6.1 * 3.2 = 19.52

Then

19.52 - 27.8 = -8.28

Now:

-8.28+11 = 2.72

I believe that would be your answer!

lol

Here are some sites I highly recommend that you use for reference!

http://www.purplemath.com/

This one is great for breaking down how you do the equations.

If you know what they called these equations like what is the lessons name because that is what you are doing.  Just wait until you get to radical expressions those things are HARD!

http://www.algebrahelp.com/

Great for scientific Calculators.  Use their complex calculators for equations like the one above!

Here is your equation on there:

http://www.algebrahelp.com/calculators/e...

Hope I Helped and Best of luck!

I also recommend that you look into finding the answer book/key for the books you are using.

It will make checking your child's work and tests a lot easier and faster! lol...

Until then the sites I gave you with the calculators will be a HUGE help!

They also have break down of how to solve every type of algebra equation as well!

Answer 4

The example you gave with the "brackets" would be worked as (6.1 * 3.2)-27.8  then add the absolute value of that answer to the 11.  That would be 19.52 - 27.8, which would be --8.28.  The absolute value of this is 8.28, + 11 = 19.28

The +/- key changes a positive number to a negative number or viceversa.

For your examples above that, we have to follow the order of operations:

Rule 1:    First perform any calculations inside parentheses.

Rule 2:    Next perform all multiplications and divisions, working from left to right.

Rule 3:    Lastly, perform all additions and subtractions, working from left to right.

For the first, it would be 3- 32 + +/- +7, which doesn't come out right, but if you miscopied and it should be -29 +/- -7 then it would come out 29 - 7 which would be 22 and it matches the second one.  If it's exactly the same as you wrote, then it would come out -22.

Doing the second one would be 7+(3-32) +/- , then 7+(-29) +/-, which comes out 22.

I think the only way I can see for them to come out the same would be if you've miscopied one of them.

If I may make a suggestion?  Get a math book with a solution key not just an answer key, or get the solution key for this one.  Solution keys show step-by-step how to work the problems.

If I may ask?  what math book are you using?