Answer:
3 2/3
Step-by-step explanation:
7(3x-4)=49
21x-28=49
21x=77
x=3 2/3
(x - 1)(x - 2)(x + 2)
note that the sum of the coefficients 1 - 1 - 4 + 4 = 0
thus x = 1 is a root and (x - 1 ) is a factor
dividing x³ - x² - 4x + 4 by (x - 1)
x³ - x² - 4x + 4 = (x - 1)(x² - 4 ) (note (x² - 4 ) is a difference of squares )
x³ - x² - 4x + 4 = (x - 1)(x - 2)(x + 2)
(x - 1)(x - 2)(x + 2 ) =0
x - 1 = 0 ⇒ x = 1
x - 2 = 0 ⇒ x = 2
x + 2 = 0 ⇒ x = - 2
solutions are x = 1 or x = ± 2
X time 0.8 (or 80 percent)= 15
so 15/0.8=X
18.75
