Explanation:
what do you not understand ? please let me know where you need more instructions.
the basic rule : every term of one side has to be multiplied with every term of the other side, and the results are added (by using the correct signs of the products).
remember :
+ × + = +
- × - = +
+ × - = -
- × + = -
(3x - 3)(5x - 4) = 3x × 5x + 3x × -4 + -3 × 5x + -3 × -4 =
= 15x² - 12x - 15x + 12 = 15x² - 27x + 12