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Даю 13 балов!!!!!

1. (11a-b)² +(9a+7b)(8a-13b) = 11²a²-b²+9a+7b·8a-13b = 121a²+9a8a-b²+7b-13b = 121a²+72a²-b²+7b-13b=193a²-7b²

2. (18x+5y)(2x-4y)-(6x-3y)² = 18x+5y·2x-4y-6²x²+3²y2 = 18x+5y·2x-4y-36x²+9y² = 10y²

3. 4x(3x-2y)-(10y-0,4x)² = 12x²-8xy-100y²+8xy-0.16x² = 11.84x²-100y²

4. (15a+2b)²-(3a-7b)(3b-5a) = 15²a+2²b²-3a-7b·3b-5a = 225a²+4b²-3a-7b·3b-5a = 225a²+4b²-8a-21b²