[nick198929]

Fellow Mathematicians,

I was wondering for let's say completing the square would a question on it be on a non-calculator paper? I'm concerned becuase i have problems to do such calculations without the aid of a calculator.

Could someone please help? Or even post some methods of solving this quadratic form without a calculator.

All comments are very much appreciated. Many thanks!

[HugsNottDrugs]

Hello Nick

I hate completing the square too. I think our exam board does put it on a non-calculator paper. The basic thing is to use the quadratic formula to complete the square leaving it at the point where you hit the square root.

Or just right some random equations down

Ours is WJEC, not the best exam board so i don't know what the others do.

I guess a basic one will be placed on there though.

[TheMeister]

On AQA its on the non-calculator.

[nick198929]

Intriguing ok. Becuase i know if i use the quadratic formula i can leave the answer both postive or negative and the square root symbol etc thus not giving the aprox answer.

But for completing the square on a non-calculator paper i'm not sure what i can do.

[Princess_me]

http://www.bbc.co.uk/schools/gcsebit...nshirev2.shtml

good explanation^^

[A_Fictitious]

If you can get good at completing the square, and quick quad formula calculating now, it will really help if you go on to do maths at a-level. Its a real time saver.

[nick198929]

Thanks alot everyone. I really appreciate this.

[clad in armour]

ahhh yes
the current GCSE'rs well good luck dudes
i can remeber my results day panic and made loads of tsr friends as a result of our common worry
we have a society!
hmmmmmm completing the square
do you mean actually solving the quadratic because if its that then I would understand why it would be on a calculator paper
but completing the square in my experience certainly doesnt need the use of a calcuator at GCSE level

[Marisa_Grace]

I do OCR and it was on the calculator paper in our recent mock.. but to be safe i would ensure that you can do it without a calculator.

[nick198929]

Ok kk thanks, Marisa. By the way Princess me posted a link and one of the questions involves solving 2x^2 + 20x + 3 = 0. I'm not entirely sure how the method is created and completed without a calculator. I have read through it but it's not making sense to me.

For the question i got 2 (x^2 + 10x) + 3 then i broke it down into 2 [(x + 5)^2 - 25] +3 but i don't know what else to do.

[electriic_ink]

Originally Posted by nick198929

Ok kk thanks, Marisa. By the way Princess me posted a link and one of the questions involves solving 2x^2 + 20x + 3 = 0. I'm not entirely sure how the method is created and completed without a calculator. I have read through it but it's not making sense to me.

x^2 + 10x + 1.5 = 0
(x+5)^2 - c = 0
x^2 + 10x + 25 - c = 0
(x+5)^2 -23.5 = 0
(x+5)^2 = 23.5
x + 5 = +/- sqrt(23.5)
x = +/- sqrt(23.5) -5

What part don't you get?

[nick198929]

Hey Electriic. It's just at the point of 2 [(x + 5)^2 - 25] +3 i'm not entirely sure what to do next. On the website it states: 2 (x + 5)2 - 50 + 3 and then 2 (x + 5)2 - 47 which i'm not sure how you get to them.

[nick198929]

Help on my previous comment would be very much appreciated. Many thanks!

[rachxl]

I'd probably say non calculator.

[electriic_ink]

Originally Posted by nick198929

Hey Electriic. It's just at the point of 2 [(x + 5)^2 - 25] +3 i'm not entirely sure what to do next. On the website it states: 2 (x + 5)2 - 50 + 3 and then 2 (x + 5)2 - 47 which i'm not sure how you get to them.

2 [(x + 5)^2 - 25] +3
2 (x + 5)^2 - 50 + 3

All that's been done to get from the first equation to the second one is that the square brackets have been multiplied out:

2 x (x+5)^2 = 2(x+5)^2
2 x -25 = -50

Thus 2 [(x + 5)^2 - 25] = 2 (x + 5)^2 - 50
And 2 [(x + 5)^2 - 25] + 3 = 2 (x + 5)^2 - 50 + 3

To get from 2 (x + 5)^2 - 50 + 3 to 2 (x + 5)^2 - 47 is fairly self-explanatory: -50+3 = -47.