

<h2>
Step-by-step explanation:</h2>
Graph B consists of a parabola that opens downward. If a parabola opens downward, the the coefficient of x will be negative.
<h2>More details:</h2>
There is an easy way to tell whether the graph of a quadratic function opens upward or downward: if the leading coefficient is greater than zero, the parabola opens upward, and if the leading coefficient is less than zero, the parabola opens downward.
-13.4 is the answer. And this is simplified form
F ` ( x ) = ( x² )` · e^(5x) + x² · ( e^(5x) )` =
= 2 x · e^(5x) + 5 e^(5x) · x² =
= x e^(5x) ( 2 + 5 x )
f `` ( x ) = ( 2 x e^(5x) + 5 x² e^(5x) ) ` =
= ( 2 x ) ˙e^(5x) + 2 x ( e^(5x) )` + ( 5 x² ) ` · e^(5x) + ( e^(5x)) ` · 5 x² =
= 2 · e^(5x) + 10 x · e^(5x) + 10 x · e^(5x) + 25 x² · e^(5x) =
= e^(5x) · ( 2 + 20 x + 25 x² )
Answer:
85 ft^2
5*6*2=60
5*5=25
25+60=85
Step-by-step explanation:
Add more details to answer
Helpful source:
https://percent-calc.com/what-is-9-of-15000