We have to solve : y^2 +3 + 12/(y^2+3)=7
y^2 +3 + 12/(y^2+3)=7
=> (y^2 + 3)^2 + 12 = 7( y^2 + 3)
=> y^4 + 9 + 6y^2 + 12 = 7y^2 + 21
=> y^4 - y^2 = 0
=> y^2( y^2 - 1) = 0
y^2 = 0 or y = 0
y^2 - 1 = 0
=> y^2 = 1
=> y = 1 and y = -1
The required real values of y are 0 , -1 and 1