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# Impossible Equation in Maths Exam watch

1. Everyone I've spoken to (including a maths teacher) says this Equation cannot be solved:

Solve this equation to find a and b:

x2 + 16x – 14 = (x+a)2 + b

a=________ b=________

it was in the OCR linear maths paper 2.

Does anyone know how to do it because it is really bugging me...
2. a=8
b=-30 (actually -78....Apologies)
tbh

Ever heard of completing the square. Good maths teacher you've got.

This is all assuming those 2's are squareds.
3. (Original post by jpjs01)
Everyone I've spoken to (including a maths teacher) says this Equation cannot be solved:

Solve this equation to find a and b:

x2 + 16x – 14 = (x+a)2 + b

a=________ b=________

it was in the OCR linear maths paper 2.

Does anyone know how to do it because it is really bugging me...
Can you use subscript or whatever it's called to show the equation properly. Thanks.
4. its completing the square

quite easy,

(x+8)^2

(x+8)(x+8)= x^2 +8x+8x+64

x^2+16-78

=(x+8)^2 -78
5. (Original post by mlbbrown)
a=8
b=-30
tbh

Ever heard of completing the square. Good maths teacher you've got.

This is all assuming those 2's are squareds.
x2 + 16x – 14 = (x+a)2 + b

(x + 8) ^2 = (x + 8) (x + 8)

= x2 + 16x + 64

Therefore,

64 - (-14) = -78

Therefore,

a= 8
b= -78
6. (Original post by mlbbrown)
a=8
b=-30
tbh

Ever heard of completing the square. Good maths teacher you've got.

This is all assuming those 2's are squareds.
7. Oh yes, it's actually been a long day - now as you mention it.
8. Yeah I think you should be having some words with your maths teacher to be honest.
9. Therefore,

a= 8
b= -78
This one.
Isn't this a standard GCSE question?
10. (Original post by jpjs01)
Everyone I've spoken to (including a maths teacher) says this Equation cannot be solved:

Solve this equation to find a and b:

x2 + 16x – 14 = (x+a)2 + b

a=________ b=________

it was in the OCR linear maths paper 2.

Does anyone know how to do it because it is really bugging me...

11. (Original post by jpjs01)
Everyone I've spoken to (including a maths teacher) says this Equation cannot be solved:

Solve this equation to find a and b:

x2 + 16x – 14 = (x+a)2 + b

a=________ b=________

it was in the OCR linear maths paper 2.

Does anyone know how to do it because it is really bugging me...
You don't even have to formally complete the square, you can do just do it by inspection:

if you expand the bracket you get x^2 + 2ax + a^2, so you know that the coefficient on x has to be equal on both sides of the equation so 2a=16 ie a=8. If a=8 a^2 is 64 and you know that 64 + b = -14 ie b=-78.

Your maths teachers must be terrible.
12. Hahaha I would swop schools if I was you, if your teacher can't solve that lol
13. (Original post by Ewan)
Hahaha I would swop schools if I was you, if your teacher can't solve that lol

bit late now eh?
14. (Original post by KwungSun)
Your maths teachers must be terrible.
I agree, seriously bad, it seems he cannot even do GCSE level maths let alone teach it.
16. Your Maths teacher isn't called Miss Martin is she?
17. (Original post by mlbbrown)
a=8
b=-30 (actually -78....Apologies)
tbh

Ever heard of completing the square. Good maths teacher you've got.

This is all assuming those 2's are squareds.
how did u get -30 before
18. lol you're predicted A* but no disrespect that was a relatively easy question.
19. im struggling to see how someone with probably a degree in maths cannot solve this?

open out your brackets and then do it by coefficients.... 2a=16 and a^2 + b = -14
20. (Original post by georgeElsworth)
im struggling to see how someone with probably a degree in maths cannot solve this?

open out your brackets and then do it by coefficients.... 2a=18 and a^2 + b = -14
It's a real shame that that's wrong...

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Updated: June 16, 2009
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