The function f(t) = -3t2 + 18t + 21 models the approximate height of an object t seconds after it is launched. How many seconds does it take the object to hit the ground?

step- i d k and i d c : )

you: : 0

bye

see explanation

step-by-step explanation:

a

(6r + 7) + (13 + 7r) ( remove brackets and collect like terms )

= 6r + 7 + 13 + 7r

= 13r + 20

b

remove brackets and collect like terms

13 - r - 1 + r

= 12 - r

c

remove brackets and collect like terms

= - 8 - r + 2r - 4

= - 12 + r

d

remove brackets and collect like terms

= 7r - - - 6r

[-   - = - - = - ]

= r -

current in the circuit at time t is /, then the power delivered to the resistor is

step-by-step explanation: