The average rate of change is up 2 over 6
Speed of boat in still water ---- x km/h
speed of current ------ y km/h
distance with the current = 4(x+y)
distance against the current = 5(x-y)
we know that 3.5(x+y) = 70
x+y = 20
but 4(x+y) = 4(20) = 80
then 5(x-y) = 80
x-y = 16
x+y=20
x-y=16
add them
2x = 36
x = 18 , then y = 2
F(3)=-18
You just replace x for three for your equation and then use Ofer of operations to solve it.
So f(3)= 21+ 2(3)-5(3)^2
The exponent goes first: f(3)= 21+ 2(3)-5(9)
Next is multiplication: f(3)= 21+ 6-45
Now add: f(3)= 27-45
Finally subtract: f(3)= -18
Hope this helps!
Answer:
i believe the answer is x= 85
