[tex]\displaystyle\bf\\1)\\\\9a^{2} -12ab=3a\cdot(3a-4b)\\\\\\2)\\\\7x-7y+ax-ay=(7x-7y)+(ax-ay)=7\cdot(x-y)+a\cdot(x-y)=\\\\=(x-y)(7+a)\\\\\\3)\\\\(x+5)(x-2)-x(x+3)=x^{2} -2x+5x-10-x^{2} -3x=-10\\\\\\4)\\\\(2x+3)(3x-7)=x(6x-3)-17\\\\6x^{2} -14x+9x-21=6x^{2} -3x-17\\\\6x^{2}-5x-6x^{2} +3x=-17+21\\\\-2x=4\\\\x=-2[/tex]
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[tex]\displaystyle\bf\\1)\\\\9a^{2} -12ab=3a\cdot(3a-4b)\\\\\\2)\\\\7x-7y+ax-ay=(7x-7y)+(ax-ay)=7\cdot(x-y)+a\cdot(x-y)=\\\\=(x-y)(7+a)\\\\\\3)\\\\(x+5)(x-2)-x(x+3)=x^{2} -2x+5x-10-x^{2} -3x=-10\\\\\\4)\\\\(2x+3)(3x-7)=x(6x-3)-17\\\\6x^{2} -14x+9x-21=6x^{2} -3x-17\\\\6x^{2}-5x-6x^{2} +3x=-17+21\\\\-2x=4\\\\x=-2[/tex]
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