-3a^2-6ab-3b^2=-3(a^2-2ab-b^2)=-3(a-ab-b)(a+ab+b)
6 1/8 * 2 2/7=784/56=14
14-12 11/19=1 8/19
1 8/19: 27= 1/19
1/19+18/19=19/19=1
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(x - 1)² - (x + 3)(x - 3 ) = x² - 2x + 1 - (x² - 9) = x² - 2x + 1 - x² + 9 = - 2x + 10