What do you mean doubling? You can add 7+7+7 which equals 21.
Given:
The power generated by an electrical circuit (in watts) as function of its current x (in amperes) is modeled by:

To find:
The current that will produce the maximum power.
Solution:
We have,

Here, leading coefficient is negative. So, it is a downward parabola.
Vertex of a downward parabola is the point of maxima.
If a parabola is
, then

In the given function, a=-12 and b=120. So,



Putting x=5 in the given function, we get




Therefore, 5 watt current will produce the maximum power of 300 amperes.
Answer:
15
Step-by-step explanation:
I don’t see any of the problems so I’m guessing you would have to rewrite it