Answer:
see below
Step-by-step explanation:
(a)
[tex]( 2x - 5 )(3x^{2} + 5x - 7)\\\\=2x(3x^2+5x-7)-5(3x^2+5x-7)\\\\=6x^3+10x^2-14x-15x^2-25x+35\\\\=6x^3+(10x^2-15x^2)+(-14x-25x)+35\\\\=6x^3-5x^2-39x+35[/tex]
(b)
[tex](2x-5)(3x^2+5x-7)=(5x-2)(3x^2+5x-7)\\\\\frac{1}{(3x^2+5x-7)}(2x-5)(3x^2+5x-7)= \frac{1}{(3x^2+5x-7)}(5x-2)(3x^2+5x-7)\\\\2x-5=5x-2\\\\2x-5x=-2+5\\\\-3x=3\\\\x=-1[/tex]
only happens when x=-1, not always