Could someone help me? I can't understand anything

I will only help with number one so you can learn how to do it. If you still dont understand, let me know and ill be here to help.

Step-by-step explanation:

> 21

what you have to do is get the x to be on its own. So we need to get rid of the 4. Since it's a fraction and fractions are division, you need to multiply both sides by 4. The reason as to why you multiply is because multiplication is the opposite if division. By multiplying both sides you get rid of the four and you are left with:

x>84

Again, let me know if you still need help.

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!