It would be the first answer. Bubble. I don't know what you call it. But yeah, it's the first one.
It gives function: h = -16t^2 + 40
water is when height is 0 so solve for 0= -16t^2 + 40
subtract 40 from both sides: -40 = -16t^2
divide by -16: -40/-16 = t^2
simplify: 5/2 = t^2
square root both sides: 1.58 = t
the orange hits the river in 1.58 seconds.
5n + 7 = 7(n+1) - 2n
First distribute 7 to all terms inside the parenthesis
7(n) = 7n
7(1) = 7
5n + 7 = 7n - 2n + 7
Simplify. Combine like terms
5n + 7 = 5n + 7
True.
If you want to continue:
Isolate the n, move all variables to one side, and constants to the other
5n (-5n) + 7 (-7) = 5n (-5n) + 7 (-7)
0 = 0
True
hope this helps
