A Level Maths Algebra Simplifying expressions help!!

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blossompr2019
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Edexcel C1 Core 1
1.1 Algebra and functions - simplifying expressions
Exercise 1A - Question 9

Hi I am studying A Level AS and A2 via fast track with Edexcel this summer. I am teaching myself the curriculum please can you help me as I was stuck with the question below:

Simplify the expression: 3x2 - 5x + 2 + 3x2 - 7x - 12
3x2 + 3x2 - 5x - 7x + 2 - 12
The correct that Edexcel states in the book says: 6x2 - 12x - 10
I thought the correct answer was 6x2 + 12x - 10
Because - 5x - 7x = +12x
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blossompr2019
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Edexcel C1 Core 1
1.1 Algebra and functions - simplifying expressions
Exercise 1A - Question 9

Hi I am studying A Level AS and A2 via fast track with Edexcel this summer. I am teaching myself the curriculum please can you help me as I was stuck with the question below:

Simplify the expression: 3x2 - 5x + 2 + 3x2 - 7x - 12
3x2 + 3x2 - 5x - 7x + 2 - 12
The correct that Edexcel states in the book says: 6x2 - 12x - 10
I thought the correct answer was 6x2 + 12x - 10
Because - 5x - 7x = +12x
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KnucBabaZongo
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(Original post by blossompr2019)
Edexcel C1 Core 1
1.1 Algebra and functions - simplifying expressions
Exercise 1A - Question 9

Hi I am studying A Level AS and A2 via fast track with Edexcel this summer. I am teaching myself the curriculum please can you help me as I was stuck with the question below:

Simplify the expression: 3x2 - 5x + 2 + 3x2 - 7x - 12
3x2 + 3x2 - 5x - 7x + 2 - 12
The correct that Edexcel states in the book says: 6x2 - 12x - 10
I thought the correct answer was 6x2 + 12x - 10
Because - 5x - 7x = +12x
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chazwomaq
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(Original post by blossompr2019)
Because - 5x - 7x = +12x
Are you sure?

What is 0 minus 5 minus 7?
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TomW624
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(Original post by chazwomaq)
Are you sure?

What is 0 minus 5 minus 7?
I think they're somehow mixing up subtraction of negatives with multiplication of negatives, not quite sure how though....

Seems like something you should know the difference between by the time you're doing A-level
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blossompr2019
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I am probably just getting mixed up with adding and subtracting negative numbers.
Ok I see what you mean thanks
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TomW624
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(Original post by blossompr2019)
I am probably just getting mixed up with adding and subtracting negative numbers.
Ok I see what you mean thanks
I think you were seeing it as -5 - (-7)
so you did the subtraction correctly and then made it positive when you should have left it as negative

The above would mean -5 + 7 = 2
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BTAnonymous
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Are you sure -5-7 = 12???

if I am in debt by £5 (so my net worth is -£5) and my debt increase by £7, my net worth now is £7 less (-£5-£7 = -£12)
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TomW624
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(Original post by BTAnonymous)
Are you sure -5-7 = 12???

if I am in debt by £5 (so my net worth is -£5) and my debt increase by £7, my net worth now is £7 less (-£5-£7 = -£12)
They had trouble subtracting negatives don't throw phrases like debt and net worth at them. They'll just get in more of a kerfuffle haha
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