Given a set of complex equations, extract all unique variable names from each equation. Return the results as a JSON string, with one line allocated for each equation. 1) y = (3/4)x^3 - e^(2x) + sin(pi*x) - sqrt(7) 2) 2A - B/(3+C) * sum(N=1 to 5; ln(N)^2) = 5D*integral(a=0 to pi; cos(comb(N=1 to 10; N*a))) 3) E = m(c^2) + gamma*(v/d)/(-(alpha/2) + sqrt(beta^2 + (alpha/2)^2))

``` json \n [ \n { \n " equation ": " y = ( 3 / 4 ) x ^ 3 - e ^( 2 x ) + sin ( pi * x ) - sq rt ( 7 )", \n " variables ": [" x ", " y "] \n }, \n { \n " equation ": " 2 A - B /( 3 + C ) * sum ( N = 1 to 5 ; l n ( N )^ 2 ) = 5 D * integr al ( a = 0 to pi ; cos ( comb ( N = 1 to 1 0 ; N * a ))) ", \n " variables ": [" A ", " B ", " C ", " D ", " integr al ", " a ", " pi ", " cos ", " comb ", " N ", " alpha ", " beta "] \n }, \n { \n " equation ": " E = m ( c ^ 2 ) + g amma *( v / d )/ (- ( alpha / 2 ) + sq rt ( beta ^ 2 + ( alpha / 2 )^ 2 )) ", \n " variables ": [" E ", " m ", " c ", " d ", " gamma ", " alpha ", " beta "] \n } \n ] \n ``` </s>