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# maths gcse factorising help watch

1. X Squared - 49

how do u factorise this into brackets
2. (Original post by Sabhani2000)
X Squared - 49

how do u factorise this into brackets
(x + 7)(x -7)
3. (Original post by Sabhani2000)
X Squared - 49

how do u factorise this into brackets
The difference of two squares
4. (Original post by Sage25)
(x + 7)(x -7)
how did u work that out?
5. (Original post by sage25)
the difference of two squares

thank you!!
6. There's no b value (ie a number of x's eg 4x) so you know that it must be difference of two squares because if you expand it out in a square they cancel out eg +7x and -7x. You then just find the square root of c (49) which is 7 and one of them must be negative if its -49
7. (Original post by Sabhani2000)
how did u work that out?
The co-efficient of x^2 is 1

so it would be have to be two single x's in the brackets like (x + a)(x + b)

Then, as the number at the end is -49, and there is no value of x it would mean a and b have to multiply to get -49 and add together to get 0

So, 7 x -7 = -49

And

7 + (-7) = 0

Therefore x^2 - 49 = (x + 7) (x - 7)
8. (Original post by sage25)
the co-efficient of x^2 is 1

so it would be have to be two single x's in the brackets like (x + a)(x + b)

then, as the number at the end is -49, and there is no value of x it would mean a and b have to multiply to get -49 and add together to get 0

so, 7 x -7 = -49

and

7 + (-7) = 0

therefore x^2 - 49 = (x + 7) (x - 7)
ow ok now i understand !
Thanks for the help!
9. (Original post by Sabhani2000)
ow ok now i understand !
Thanks for the help!
No problem!

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