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Need help with Maths homework again please


Friar

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  • 1. DDz Quorum

This time its Solving equations

My 12 yr old daughter has an algebra work sheet.

as an example here is one of the questions

5x - 5 = 16 + 2x

I seem to remember something about moving stuff to the other side of the equals sign, which changes its sign, but thats about it.

Could someone run through the steps so that I understand what you would go through to solve this type of sum please.

Cheers guys

Friar

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group your "like" terms together; get the "x"'s on one side, and the numbers on the other, typically the "x"'s on the left equal to the number on the right.

for this one....

5x - 5 = 16 + 2x

1. Subtract 2x from both sides:

5x - 2x - 5 = 16 + 2x - 2x (the 2x's on the right now cancel each other out; they = 0)

3x - 5 = 16

2. Now, add 5 to both sides:

3x - 5 + 5 = 16 + 5

3x = 21

3. Now, you need to divide out the 3 on both sides...

3x/3 = 21/3

x = 7

I'll post a diagram that shows how this works if you need it - I find that understanding why this happens helps internalize the math rather than just "following the rules."

Cheers, mate!

PS - check the answer is correct by putting the 7 back in the original problem, and both sides should equal each other.

5x7 - 5 = 16 + 2x7

35 - 5 = 16 + 14

30 = 30

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  • 1. DDz Quorum

Thanks m8, I was hoping you would be available.

So if I think I understand it....

x - 4 = 41 - 4x

x + 4x - 4 = 41

x + 4x = 41 + 4

x + 4x = 45

5x = 45

x=9

9-4 = 41 - 4x9

5 = 41 - 36

5 = 5

would that be right, not sure on the method though !

Cheers.

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This is a 'newer' way of teaching algebra, called 'algebra tiles.' If it confuses, go back to just using the regular algebra notation.

[attachthumb=1]

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Diagrams with balances also work well. Check out this website for help.

http://nlvm.usu.edu/en/nav/frames_asid_201_g_4_t_2.html

22_b5d749be83b39eb6ffd7eaaf82b0e176

22_d44b94d924a1302e01e37408c138c267

22_4efad93027f2d58a4ce6ee41e6a24315

22_c6beabfba1985908030c487e2309402c

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Thanks m8, I was hoping you would be available.

So if I think I understand it....

x - 4 = 41 - 4x

x + 4x - 4 = 41

x + 4x = 41 + 4

x + 4x = 45

5x = 45

x=9

9-4 = 41 - 4x9

5 = 41 - 36

5 = 5

would that be right, not sure on the method though !

Cheers.

That way works perfectly fine, mate.

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Don't be sad; it's natural to feel wierd when you're a math-geek-prodigy. You're well above average in that regard mate, and it's only one of your talents!

Dang if you don't know your way around a computer too - must be some link there.....

Cheers, and have a good sleep - you'll have formulae running through your head all night long now!!!   

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  • 1. DDz Quorum

~S~ Colin M8,

This is the site I use to help Jonathan out with such perplexing homework:

www.themathpage.com/alg/rules-of-algebra.htm

Its really simple to follow ,(obviously ! LOL ;)), it also has lots of examples to try as you go along.

Hope that helps.

~S~ Brainless

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