Simplify (2x – 2y)(2y + 8) = ? a. 4xy – 4y2 b. 4xy – 16x – 4y2 – 16y c. 4xy + 16x + 4y2 + 16y d. 4xy + 16x – 4y2 – 16y

D is the correct answer.

D. 4xy + 16x – 4y2 – 16y

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)