Arock is thrown straight up into the air from a height of 4 feet. the height of the rock above the ground, in feet, t seconds after it is thrown is given by -16t^2+56t+4. for how many seconds will the height of the rock be at least 28 feet above the ground?

my answer is$ 12

step-by-step explanation:

because 15 -2=12

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!

32.5 is the answer i got thats the answer

hey i have you need to go to the lesson of the dba and go to page 4 there should be cards and they have questions on them and if you click them there will be the answers and you can use that for the dba

step-by-step explanation: