Which is a linear equation? a) x squared + y = 4 b) x + y = 4 c) xy = 4 d) 1/x + y = 4

B. Re arranger, it is y = 4 - x

Since x does not have a number above or below it, either as a fraction or a exponent, the equation is linear.
A has an exponent
C and C both result in fractions involving x

Do the inverse operation