Find the value of (5a-7b)^3+(9c-5a)^3+(7b-9c)^3
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(5a-7b)³+(9c-5a)³+(7b-9c)³
=5a³-7b³-3(5a)²(7b) +3(5a)(7b) ²+{9c³-5a³-3(9c)²(5a) +3(9c)(5a) ²}+{7b³-9c³-3(7b)²(9c) +3(7b)(9c) ²}
=125a³-343b³-525a²b+735ab²+729c³-125a³-1215ac²+675a²c+343b³-729c³-1323b²c+1701bc²
=-525a²b+735ab²-1215ac²+675a²c-1323b²c+1701bc²
=5a³-7b³-3(5a)²(7b) +3(5a)(7b) ²+{9c³-5a³-3(9c)²(5a) +3(9c)(5a) ²}+{7b³-9c³-3(7b)²(9c) +3(7b)(9c) ²}
=125a³-343b³-525a²b+735ab²+729c³-125a³-1215ac²+675a²c+343b³-729c³-1323b²c+1701bc²
=-525a²b+735ab²-1215ac²+675a²c-1323b²c+1701bc²
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