<span>You're 9 miles ahead when the 2nd bike starts.
His speed wrt you is 3 mph (12-9).
9/3 = 3 hours
I hope i helped you
</span>
All we need is to put this form in the vertex form f(x) = (ax+b)^2 + c
So we have <span>f (x)= 3x^2+12x+11 ....
Let's complete the square (if you aware of it)
</span><span>
f(x)= 3x^2+12x+11 = 3(x^2+4x)+11 = 3(x^2+4x+4-4)+11
=</span><span> 3([x^2+4x+4]-4)+11 = 3[(x+2)^2-4]+11 =3</span><span>(x+2)^2 - 12 +11 = 3</span><span><span>(x+2)^2 -1
so our form would be:

Here is a parabola with vertex of (-2,-1) and with positive </span> slope (concave up)
</span>
I hope that
helps!
Answer:
Step-by-step explanation:
C= 2 *3.14*r
we have diameter 2r=d=18
C=18*3.14
C=56.52
Hope you can see the picture please let me know if you can Have a great day