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))

``` \n { \n " 1 ) ": [" x ", " y ", " e ", " pi ", " sqrt ( 7 ) "], \n " 2 ) ": [" A ", " B ", " C ", " N ", " ln ( N )", " D ", " a ", " pi ", " comb ( N = 1 to 1 0 ; N * a ) "], \n " 3 ) ": [" m ", " c ", " d ", " v ", " alpha ", " beta ", " gamma "] \n } \n `` ` </s>