Factorise x^2 + 4x +3
First take the 4x - the two numbers that will be +/- to the x in the brackets will need to add to form this number, so the possibilities are 1 and 3 or 2 and 2.Now take the 3 - the two numbers that will be +/- to the x in the brackets will need to multiply to form this number, so 1 and 3.The number in combination in common is 1 and 3, giving us the answer (x+1)(x+3)
JS
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Jo wants to work out the solutions of x^2 + 3x – 5 = 0 She says, ‘‘The solutions cannot be worked out because x^2 + 3x – 5 does not factorise to (x + a)(x + b) where a and b are integers.’’ Is Jo correct?