linear means first degree
first degree means the hightest exponent of the variables is 1
so
equation 1:
[tex]y=2x^2+1[/tex]
highest exponent is 2, not 1
not leinear
equation 2: y^2=3x+1
highest exponent is 2, not 1
not linear
equaton 3 y=5x-1
y=5x^1-1, it is 1
it is linear
equaton 4
y=4x^4-1
highest is 4, not 1
not linear
answer is equation 3: y=5x-1
