$In$ each part, determine whether the equation $is$ linear $inx$

and $y.$

$(a)2^{\frac{1}{3}}x+\sqrt[\phantom{2}]{3}y=1$

$(b)2x^{\frac{1}{3}}+3\sqrt[\phantom{2}]{y}=1$

$(c)cos(\frac{}{7})x-4y=log3$

$(d)\frac{}{7}cosx-4y=0$

$(e)xy=1$

$(f)y+7=x$