(а-х)(а+х)(а^2 + х^2)=(а^2 - x^2)(a^2 + x^2) = a^4 +a^(2)x^(2)-a^(2)x^(2) - x^4 = a^4 - x^4
4) 35x^2y/12ab*8ab^3/7xy=5x/3*2b^2=10b^2x/3
5) -6xy^3/5ab*10ab/9x^2y^2=-2y*2/3x=4y/3x
6) 3b*b^2/2xa=3b^3/2xa
3a²-9ab=3a(a-3b)
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5x -5a =45+5x
5x-5x=45+5a
5a+45=0
5a=-45
a= - 9
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5x+45=45+5x
0*x=0
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ответ при а = - 9