Will give brainliest if your right A scientist conducts an experiment to observe the half-life period of the radioactive element barium. He starts the experiment with 200 grams of barium and records the mass at the end of every thirteen day. After how many days is the mass of barium closest to 1.5 grams?​

It would be 91 days

Step-by-step explanation:

Hope this helps :)

you already gave the answer

step-by-step explanation:

hello from mrbilldoesmath!

answer:

25x^2 + 90x + 84

discussion:

mn(x) = m(n(x)) = m( 5x + 9) =

(5x + 9)^2 + 3 =>

25x^2 + 90x + 9^2 + 3 =

25x^2 + 90x + 84                 (as 9^2 = 9*9 = 81)

which is the second choice

regards,  

mrb

p.s.   i'll be on vacation from friday, dec 22 to jan 2, 2019. have a great new year!