x^2 + 15x + 56
Good way to factor quadratic functions:
In a function x^2 +bx + c
Find two number that when multiplied together will form c (in our case 56) and that when added together form b (in our case 15)
Number 1 x Number 2 = 56
Number 1 + Number 2 = 15
Number 1 = 8
Number 2 = 7
(It'll be easier to find these numbers with practice)
Now in the function instead of bx, split it and use (number 1)x + (number 2)x
It's allowed because it's the same value since N1 + N2 = bx already
x^2 + 15x + 56
Now is:
x^2 + 8x + 7x + 56
Now you can factor this function much easily because it can transformed into:
(x + 8)(x) + (x + 8)(7)
x + 8 is the common factor
it can become:
(x + 8) (x + 7)
The sides of the rectangle are 8 and 7
Hope this helps you with factoring :)
