(x - 12)(x + 4) = 9
x² + 4x - 12x - 48 = 9
x² - 8x - 48 = 9 |add 48 to both sides
x² - 8x = 57
x² - 2x · 4 = 57 |add 4² to both sides
x² - 2x · 4 + 4² = 57 + 4² |use (a - b)² = a² - 2ab + b²
(x - 4)² = 57 + 16
(x - 4)² = 73 ⇔ x - 4 = √73 or x - 4 = -√73 |add 4 to both sides
x = 4 + √73 or x = 4 - √73
The answer is 42 cause you do ( 18*28=12x) wich is 504=12x which equals 42
Answer:
C i think
Step-by-step explanation:
It should be 3cm if I did it right
it's the only one that hasn't been with a positive 2
