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# completing the square watch

1. So i was followingan example from the C1 textbook and understood untill a certain point.

2x^2 +10x +7=0 so they take a fcator of 2 out to give 2(x^2+5x)+7

then half b 2(x+5/2)^2 -25/4 +7

I dont understand this next bit: 2(x+5/2)^2 -25/2 +7 = 2(x+5/2)^2 -11/2 How did the -25/4 turn into -25/2 ?
2. umm hold on i'll have to write that down
3. okay i'm confused too..
my answer to that question would be (x +2.5)^2+9.75 hmmmm... is this for AS level? i'm taking AS level too :s
4. (Original post by hazbaz)
So i was followingan example from the C1 textbook and understood untill a certain point.

2x^2 +10x +7=0 so they take a fcator of 2 out to give 2(x^2+5x)+7

then half b 2(x+5/2)^2 -25/4 +7

I dont understand this next bit: 2(x+5/2)^2 -25/2 +7 = 2(x+5/2)^2 -11/2 How did the -25/4 turn into -25/2 ?
they've converted the +7 into a fraction, +14/2, so -25/2 + 14/2 = -11/2
5. (Original post by thegodofgod)
they've converted the +7 into a fraction, +14/2, so -25/2 + 14/2 = -11/2
Ye but origionally the number was -25/4 and 7 & so surly they need to make the 7 a common denominator to get 28/4 and do it that way?
6. (Original post by foldingstars45)
okay i'm confused too..
my answer to that question would be (x +2.5)^2+9.75 hmmmm... is this for AS level? i'm taking AS level too :s
Ye it is i think i get it now though what A levels are you doing?
7. (Original post by hazbaz)
Ye it is i think i get it now though what A levels are you doing?
haha, was mine wrong then?
andd i'm doing 3 sciences and maths but taking physics was a big mistake u?
8. (Original post by foldingstars45)
haha, was mine wrong then?
andd i'm doing 3 sciences and maths but taking physics was a big mistake u?
I think so it was what the previous poster said . And nah Physics is amazing. I'm doing Maths chemistry Physics History and depending how i do in C1 imma start further Maths and do that poissbly up to A2 but defo for AS
9. (Original post by hazbaz)
I think so it was what the previous poster said . And nah Physics is amazing. I'm doing Maths chemistry Physics History and depending how i do in C1 imma start further Maths and do that poissbly up to A2 but defo for AS
oh i wish i'd took history instead of physics! but it's too late now.. maybe i'll take it up for AS next year. what grades did you get in gcse?
10. (Original post by foldingstars45)
oh i wish i'd took history instead of physics! but it's too late now.. maybe i'll take it up for AS next year. what grades did you get in gcse?
But Physics is good! and 9A*'s 2A's you?
11. (Original post by hazbaz)
But Physics is good! and 9A*'s 2A's you?
nah i'm just not so interested anymore :/ and woah! that's amazing, i got 4a*s and 6 a's
12. (Original post by foldingstars45)
nah i'm just not so interested anymore :/ and woah! that's amazing, i got 4a*s and 6 a's
Its ok and well done!

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