Answer:
(B)
4 +/- 3 sqrt(2) or 4+3sqrt(2) and 4-3sqrt(2)
Step-by-step explanation:
4(c-4)^2=72
4(c-4)(c-4)=72
foil the parenthesis (first, outside, inside, last)
4(c^2 -4c -4c +16)=72
4(c^2-8c+16)=72
divide each side by 4
c^2-8c+16=18
subtract 18 from both sides
c^2-8c-2
use quadratic formula
((-b +/- sqrt((-b^2)-4ac)))/2a
((-(-8)+/-sqrt((-8)^2-4(1)(-2)))/2(1))
(8+/-sqrt(64-(-8)))/2
(8+/-sqrt(64+8))/2
(8+/-sqrt(72))/2
(8+/-sqrt(36 * 2))/2
(8+/-6sqrt(2))/2
4+/-3sqrt(2)
or 4+3sqrt(2) and 4-3sqrt(2)
