The microphone was $126.
You would multiply $38 by 6 which equals $228.
Then do $354-$228 which equals $126.
Answer:
A general exponential equation is written as:
f(x) = A*(r)^x
Where:
A is the initial value, this is the value that the function takes when x = 0.
r is the rate of growth
x is the variable.
In this case, the function is:
f(x) = 2*(4)^x
The initial value is:
f(0) = 2*(4)^0 = 2*1 = 2
The initial value is 2.
And the rate of growth is 4.
So Martin seems to mixed these two values (he said initial value = 4, and rate = 2, which is the opposite of what we found)
192 in2
The formula for surface area is 2(lw + wh + hl) = 2(2*8 + 12*8 + 12*2) = 2(16+56+24) = 2(96) = 192