X2 is double the amount of x1
Answer:
Paolo made an error when he cross multiplied the proportion
Step-by-step explanation:
The proportion is ...

"Cross multiply" means "multiply both sides of the equation by the product of the denominators."

The last time David filled up his truck with gas, he paid $27.44 for 7 gallons. This time, he needs 15 gallons. If the price is the same, how much will he pay?
When I see the words "instantaneous rate of change", I have to assume that you're in some stage of pre-calculus in your math class.
The instantaneous rate of change of a function is just its first derivative.
We have the function
V(r) = 3 π r²
and we need its first derivative with respect to ' r '. That shouldn't be
too hard, because the ' 3 π ' is nothing but constants.
Watch me while I do it slowly for you:
-- The derivative of ' r² ' with respect to ' r ' is ' 2r '.
-- The derivative of V(r) with respect to ' r ' is (3 π) times the derivative of ' r² '.
-- The derivative of V(r) with respect to ' r ' is (3 π) times (2r) = <u>6 π r</u> .
The value of the derivative when r=3 is (6 π 3) = 18π = about <em>56.5 feet³/foot .</em>
But it is not a complete question.