Answer:
(x+9)(x+3)
Step-by-step explanation:
first of all, you should learn this properly, because you'll have to go back to this over and over again. anyways
you need to find two numbers so that it adds up to 12, but also multiplies to 27.
The numbers 9 and 3 fit the situation
So you add 9x and 3x because it's the same thing as 12x. you're just splitting up the term 12x into two other terms.
so now it looks like x^2 + 9x + 3x + 27. now you factor the first two terms and last two terms
x ( x + 9 ) <---factor of first two terms
3 ( x + 9) <---factor of last two terms
x(x+9)+3(x+9)
you notice that (x+9) is common in both factorized parts
so, you add x and 3 from the outside
and you get (x +3 ) (x+9)