Factorise x² + 2x - 8
Since an x² is produced, we know that the factorised version will be (x+a)(x+b). To find a and b we need to consider the relationship between 2 and -8. It is going to be factorised into two brackets, due to the x², so we need to break the 2 down into 2 numbers that will add to give 2 and multiply together to give -8. The 8 is negative so one of these numbers must also be negative. These 2 numbers must be 4 and -2. Then substitude these numbers in to be a and b so the equation factorised is (x+4)(x-2)
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