Question

Сделать 4 задания, 88 баллов
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Answer 1

$\displaystyle\bf\\1)\\\\\frac{8a^{9} }{b^{2} } :\frac{4a^{3} }{b^{2} } =\frac{8a^{9} }{b^{2} }\cdot\frac{b^{2} }{4a^{3} }=2a^{9-3} =2a^{6} \\\\2)\\\\y=\frac{8}{x}\\\\3)\\\\\frac{y}{x^{2} - y^{2} }+\frac{1}{x+y}= \frac{y}{(x - y)\cdot(x+y) }+\frac{1}{x+y}= \\\\\\=\frac{y+x-y}{(x-y)(x+y)} =\frac{x}{x^{2} - y^{2} } \\\\4)\\\\\sqrt{36x} -\sqrt{49x}+\sqrt{x} +\sqrt{16x} =\\\\\\= \sqrt{36x} -\sqrt{49x}+\sqrt{x} +\sqrt{16x} =$

$\displaystyle\bf\\=\sqrt{6^{2}\cdot x} -\sqrt{7^{2}\cdot x}+\sqrt{x} +\sqrt{4^{2}\cdot x} =\\\\\\=6\sqrt{x} -7\sqrt{x} +\sqrt{x} +4\sqrt{x} =4\sqrt{x}$