Answer:

Step-by-step explanation:
2x-y=7
y=2x+3
Substitute (2x+3) in for y in the first equation
2x-(2x+3)=7
2x-2x-3=7
-3=7
Becuase -3 does not equal 7 the answer is no solution
Answer:
Radiation 1- Function
Radiation 2- Not a function
Radiation 3- function
Radiation 4- function