Answer:
b. y^2 = x^2 + 3 not a linear equation
Explanation:
Linear equations are equations in which the variable is in the first degree, or only to the first power.
a. y = x + 6 Nothing above the first power
b. y^2 = x^2 + 3 X and y are to the second power
c. x = 5 Only to the first power
d. 2x = 3y Only to the first power