<em>1. </em><em>(11a-b)² +(9a+7b)(8a-13b) = </em><em>11²a²-b²+9a+7b·8a-13b = 121a²+9a8a-b²+7b-13b = 121a²+72a²-b²+7b-13b=193a²-7b²</em>
<em>2.</em><em> (18x+5y)(2x-4y)-(6x-3y)² = </em><em>18x+5y·2x-4y-6²x²+3²y2 = 18x+5y·2x-4y-36x²+9y² = 10y²</em>
<em>3. </em><em>4x(3x-2y)-(10y-0,4x)²</em><em> = 12x²-8xy-100y²+8xy-0.16x² = 11.84x²-100y²</em>
<em>4. </em><em>(15a+2b)²-(3a-7b)(3b-5a) </em><em>= 15²a+2²b²-3a-7b·3b-5a = 225a²+4b²-3a-7b·3b-5a = 225a²+4b²-8a-21b²</em>
<span>3х^2-8х-2=</span><span>х^2-4⇒2</span><span>х^2-8x+2=0⇒x^2-4x+1=0⇒
D/4=2^2-1=3; √D/4=√3⇒
x1=2-√3; x2=2+√3</span>
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B умножить на (2a в квадрате -1)
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2
Решение в приложении..........