Question

b²-18b+81
—————
b²-81.


a²+2ab+b²
—————
a²-b²


x²-9
———
3-x.

(a-c)
——
c-a²​

Answer 1

На фото................

Answer 2

$\displaystyle\bf\\1)\\\\\frac{b^{2}-18b+81 }{b^{2} -81} =\frac{b^{2} -2\cdot b\cdot 9+9^{2} }{b^{2} -9^{2} } =\frac{(b-9)^{2} }{(b-9)\cdot(b+9)} =\frac{b-9}{b+9} \\\\2)\\\\\frac{a^{2} +2ab+b^{2} }{a^{2} - b^{2} } =\frac{(a+b)^{2} }{(a+b)\cdot(a-b)} =\frac{a+b}{a-b} \\\\3)\\\\\frac{x^{2} -9}{3-x} =-\frac{x^{2} -3^{2} }{x-3} =-\frac{(x-3)\cdot(x+3)}{x-3} =-(x+3)\\\\4)\\\\\frac{a-c}{c^{2} -a^{2} } =-\frac{c-a}{(c-a)\cdot(c+a)} =-\frac{1}{c+a}$