hi <3
i'm not sure of which method you will have been taught but i'll try to explain the method i was shown.
so, you need to multiply the coefficient of x^2 by the last value
3 x -12 = -36
now, you need to find two values that multiply to make -36 but add to make 5.
9 and 4 would work. it would have to be positive 9 and negative 4, as these would subtract to give the 5 that you need
now we have:
(x - 4)(x + 9)
however, we need to achieve the 3 from somewhere so it needs to be divided somewhere
9 is divisible by 3 so you can divide it there. as 4 cannot divide by 3, you would move the 3 up to be the coefficient.
thus, your final answer would be:
(3x - 4)(x + 3)
hope this helps :)
