Answer:
Step-by-step explanation:
You would substitute "2x" for every "x" in the function in the same way you would substitute any other number.
So if f(x)=Sqrt[7x²-3x], then: f(2x)=Sqrt[7(2x)²-3(2x)]
=Sqrt[7(4x²)-3(2x)]
=Sqrt[28x²-6x]
84 feet
-16(1.5)^2+120=84
a=5
x=4
ax+3=23
5×4+3=23