Answer:
The answer is (x + 3) (x - 7) = 0
Step-by-step explanation:
x² - 4x = 21
x² - 4x - 21 = 0
x² - 7x + 3x - 21 = 0
x(x - 7) + 3(x - 7) = 0
(x + 3) (x - 7) = 0
Thus, The answer is (x + 3) (x - 7) = 0
<em><u>-TheUnknownScientist</u></em>
I believe it’s B . Not 100 percent sure but yeah
Answer:
Step-by-step explanation:
Brittany paints the room in x hours, completing 1/x of the room per hour.
Ashley paints the room in x+2 hours, completing 1/(x+2) of the room per hour.
Working together, they complete 1/x + 1/(x+2) = ⅐ of the room per hour.
7(x+2) + 7x = x(x+2)
14x + 15 = x^2 + 2x
x^2 - 12x - 15 = 0
x = [12 ±√(12²+60)]/2= 6±√51
6-√51 is an extraneous solution.
x = 6+√51 ≈ 13.14
Brittany paints the room in 12.14 hours
