Factorise x^2 + 3x -28
[Method 1] The solutions need to add together to make 3 and multiply to make -28. For them to multiply and make a negative number one of the solutions must also be negative and the other positive (so there are two solutions total). Things that multiply to make -28 are 4 X -7, -4 X 7, 2 X -14, -2 X 14. If we add up each of these indivudally only 7 - 4 makes 3 which is what we want for the eqaution above. We can then write the answer as (x+7)(x-4).[Method 2] Use the quadratic formula to find the solutions to this equation are -7 and 4. From there we can form the brackets by reversing the +/- and writing (x+7)(x-4).
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