The noise level, N, at a distance d metres from a single sound source of loudness L is given by the formula
N=L/d^2
Two sound sources, of loudness L1 and L2 are placed m metres apart.
The point P lies on the line between the sound sources and is x metres from the
sound source with loudness L1.
(i) Write down a formula for the sum of the noise levels at P in terms of x. 1
(ii) There is a point on the line between the sound sources where the sum 4 of the noise levels is a minimum.
Find an expression for x in terms of m, L1 and L2 if P is chosen to be this point.

Question

The noise level, N, at a distance d metres from a single sound source of loudness L is given by the formula
N=L/d^2
Two sound sources, of loudness L1 and L2 are placed m metres apart. 
The point P lies on the line between the sound sources and is x metres from the
sound source with loudness L1. 
(i)	Write down a formula for the sum of the noise levels at P in terms of x.	1
(ii)	There is a point on the line between the sound sources where the sum	4 of the noise levels is a minimum.
Find an expression for x in terms of m, L1 and L2 if P is chosen to be this point.