Ariana starts with 100 milligram of a radioactive substance the amount of the substance decreases by 20% each week each number for weeks w. the expression 100 (-0.2) finds the amount radioactive substance remaining w weeks.

The required expression is 100 - 0.2w

Step-by-step explanation:

Given,

Amount of radioactive substance = 100 mg

The substance decreases by 20% each week.

To find the remaining amount of the in w weeks.

Now,

Each week 20% = 0.2 of the substance will be decreased.

So, in w weeks 0.2×w of the the substance will be decreased.

Hence,

The remaining substance = 100 - 0.2w

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!