This expression is a difference of squares:
<span>From my research, the question had the following choices:
the number of songs played on each channel
the weather conditions of the city
the number of music lovers in the city
the duration of each concert
Among the choices, the correct answer is "the number of music lovers in the city". The more concerts there are in a city corresponds to the number of music lovers. Radio channels usually play music, so having a lot radio channels in a city must mean that there is a large audience.</span>
Well, It would be hard to write out the formula and everything here so I wrote it out for you! Work shown!
You can use the discriminant rule, which is :
b^2 -4ac
“exactly one solution” means that it is equal to zero
so:
b^2 -4(4)(9)=0
b^2 -4(36)=0
b^2 -144=0
b^2=144
square root both sides
b=12 or -12
hope this helps !