Question

решите A2 A3 A4 Алгебра 8 класс

Answer 1

$\displaystyle\bf\\A2)\\\\\frac{b^{2} }{b^{2} -9} -\frac{b}{b-3} =\frac{b^{2} }{(b-3)(b+3)} -\frac{b}{b-3} =\frac{b^{2}-b\cdot(b+3) }{(b-3)(b+3)} =\\\\\\=\frac{b^{2}-b^{2} -3b }{b^{2}-9 } =-\frac{3b}{b^{2} -9} \\\\\\A3)\\\\\frac{m}{m^{2}-4 } +\frac{2}{(m-2)^{2} } =\frac{m}{(m-2)(m+2)} +\frac{2}{(m-2)^{2} } =\\\\\\=\frac{m\cdot(m-2)+2\cdot(m+2)}{(m+2)(m-2)^{2} } =\frac{m^{2} -2m+2m+4}{(m+2)(m-2)^{2} } =\\\\\\=\frac{m^{2} +4}{(m+2)(m-2)^{2} }$

$\displaystyle\bf\\A4)\\\\a+b-\frac{a^{2}+b^{2} }{a-b} =\frac{(a+b)(a-b)-(a^{2} +b^{2} )}{a-b} =\\\\\\=\frac{a^{2}-b^{2} -a^{2} -b^{2} }{a-b} =-\frac{2b^{2} }{a-b} =\frac{2b^{2} }{b-a}$