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Algebra

fliss1992

Here goes:

I have a question that I'm not sure of the answer, here is how I've worked it out and the answer I have..

x/9 = 2

The answer I got for x is 33?

I worked it out like this..

x/9 x 3 = 2 x 3 9 x 3 = 27 2 x 3 = 6

27 + 6 = 33

I think this is wrong, if so can somebody show me how I went wrong.

I also have another question, but don't have a clue how to work it out..

72/x^3 - 9 = 1

Thanks

Reply 1

m4ths/maths247

7

Is 33 divided by 9 equal to 2?

Reply 2

Ché.

Original post by m4ths/maths247

Is 33 divided by 9 equal to 2?

Yeah?
Is it?
You've actually confused me on how you cannot grasp the basic algebraic concepts/laws... :frown:

What really confused you on that question in particular?

There is no point moving on to the second problem if you can't independently solve the ones of equivalent basic level.

PRACTICE!

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(edited 9 years ago)

Reply 3

m4ths/maths247

7

Original post by Ché.

Yeah?
Is it?
You've actually confused me on how you cannot grasp the basic algebraic concepts/laws... :frown:

What really confused you on that question in particular?

There is no point moving on to the second problem if you can't independently solve the ones of equivalent basic level.

PRACTICE!

Posted from TSR Mobile

I am a little lost.

Reply 4

fliss1992

OP

2

no it's not equal to two, I never said the question was right, in fact I said it was wrong in my eyes!

I have the answer as 22 for the equations..

Reply 5

1144297

9

Original post by fliss1992

Here goes:

I have a question that I'm not sure of the answer, here is how I've worked it out and the answer I have..

x/9 = 2

The answer I got for x is 33?

I worked it out like this..

x/9 x 3 = 2 x 3 9 x 3 = 27 2 x 3 = 6

27 + 6 = 33

I think this is wrong, if so can somebody show me how I went wrong.

I also have another question, but don't have a clue how to work it out..

72/x^3 - 9 = 1

Thanks

Hi!

I looked over your working, and I do not quite understand why you did what you did. I assume that you understand that you multiply both sides (x/9 x 3 = 2 x 3) however then you sail off and do the wrong thing.

Firstly, you could have just multiplied each side by 9, (as you move it across) and got (x*9)/9 = 2*9, and the 9/9 would cancel and leave x = 18. But, just to avoid confusion, I will go over your way.

You start with multiplying them by 3, which would work, but you multiply 9 - you would multiply the x on top, to get (3x/9)=(2*3), which simplified to be (x/3) = 6. From this you can just do 3*6 to get 18, which matches the original. We can check our working by putting our value (18) into the original formula.

18/2 = 9.

Which works.

As for the second problem, while I will not work it out for you, you can use the same rules. Remember BIDMAS (Brackets, Indices, Divide, Multiply, Add, Subject) as your order, and just to be sure, when
a/b=x
then
a/x=b
ie, 1/3=x, 1/x=3

With them rules, it should be quite easy to solve the second. If you need any more help, just say.

Good luck!

Ten People (ThatPerson2)

Reply 6

m4ths/maths247

7

Original post by fliss1992

no it's not equal to two, I never said the question was right, in fact I said it was wrong in my eyes!

I have the answer as 22 for the equations..

When I asked that question I am asking it to allow you to build understanding.
When solving an equation the final step is to check if the value you have found 'satisfies' the equation. (ie it works, or its right).

Taking your question:
Some number is divided by 9 to give 2
What is the opposite (or inverse) of dividing?

Solving equations in these case is carrying out inverse operations.

Reply 7

QuantumSuicide

Dis guy must be trolling. Surely.

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Reply 8

fliss1992

OP

2

the opposite to divide is times, but I don't know where I'm meant to do that?

OP

who's trolling?

Original post by QuantumSuicide

Dis guy must be trolling. Surely.

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With less than 60% of students obtaining C grades or higher in GCSEs nationally I am not suprised people may struggle with this.

Reply 11

m4ths/maths247

7

Original post by fliss1992

the opposite to divide is times, but I don't know where I'm meant to do that?

Right, start here:
https://www.youtube.com/watch?v=Rb6n22UjAKY

Then:
https://www.youtube.com/watch?v=1OEMSfr1cvQ

Reply 12

QuantumSuicide

Original post by m4ths/maths247

With less than 60% of students obtaining C grades or higher in GCSEs nationally I am not suprised people may struggle with this.

That's a bit surprising yo. Where did you get that statistic from?
I apologise to da OP if you weren't trolling, my friend.

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Reply 13

m4ths/maths247

7

Original post by QuantumSuicide

That's a bit surprising yo. Where did you get that statistic from?
I apologise to da OP if you weren't trolling, my friend.

Posted from TSR Mobile

National stats.
Its about 56% each year who get a C or higher.
Many different reasons for the 44% not getting there.
Fair play to the OP for signing up to a forum and looking for help. The questions do seem troll like for able mathematicians but far from troll like when you actually meet kids on a daily basis. :smile: