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1. Is this quadratic factorisable? And in what other ways can we solve this? Im confused =/

Thanks

6x²-5x-15=0
2. No.

Either complete the square, or the use the quadratic formula.
3. (Original post by xXxiKillxXx)
Is this quadratic factorisable? And in what other ways can we solve this? Im confused =/

Thanks

6x²-5x-15=0
It doesn't factorise. (nicely)
one way you can do it is by completing the square
have you been taught how to complete the square?
4. (Original post by Sliced Bread)
It doesn't factorise. (nicely)
one way you can do it is by completing the square
have you been taught how to complete the square?
Ermm noo... can u show me for this question please?
5. (Original post by xXxiKillxXx)
Ermm noo... can u show me for this question please?
6x^2 -5x - 15 = 0

now make it so that the x has a coefficient of 1

so divide by 6

x^2 -(5/6)x - 15/6

we do this because 1 is a square number.
what you have to do now is use the fact that for any two numbers a and b,

(a+b)(a-b) = a^2 - b^2 (check it by multiplying out by whatever method you use)

so if you can get this expression in the format a^2-b^2, you can definitely factorise it to find the answer

now in the above expression if you let a = (x- 5/12), then what would b be? (substitute it in)

and hence using the difference of two squares above, you can put it into a factorised format.
6. (Original post by Sliced Bread)
6x^2 -5x - 15 = 0

now make it so that the x has a coefficient of 1

so divide by 6

x^2 -(5/6)x - 15/6

we do this because 1 is a square number.
what you have to do now is use the fact that for any two numbers a and b,

(a+b)(a-b) = a^2 - b^2 (check it by multiplying out by whatever method you use)

so if you can get this expression in the format a^2-b^2, you can definitely factorise it to find the answer

now in the above expression if you let a = (x- 5/12), then what would b be? (substitute it in)

and hence using the difference of two squares above, you can put it into a factorised format.
Thank you so much! I got it now!

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