Question

Допоможіть, будь ласка!!!

Answer 1

$\displaystyle\bf\\1)\\\\\sqrt[7]{3+2\sqrt{2} } \cdot\sqrt[7]{3-2\sqrt{2} } =\sqrt[7]{(3+2\sqrt{2} )\cdot(3-2\sqrt{2}) } =\sqrt[7]{3^{2}-(2\sqrt{2} )^{2} } =\\\\=\sqrt[7]{9-8} =\sqrt[7]{1} =\boxed1\\\\\\2)\\\\16^{0,75} +25^{-0,5} =\Big(2^{4} \Big)^{0,75} +\Big(5^{2} \Big)^{-0,5} =2^{3} +5^{-1} =8+0,2=\boxed{8,2}\\\\\\3)\\\\Sin85^\circ Cos25^\circ-Cos85^\circ Sin25^\circ=Sin\Big(85^\circ-25^\circ\Big)=Sin60^\circ=\boxed{\frac{\sqrt{3} }{2}} \\\\\\4)\\\\y=Cosx-5$

$\displaystyle\bf\\-1\leq Cosx\leq 1\\\\-1-5\leq Cosx-5\leq 1-5\\\\-6\leq Cosx-5\leq -4\\\\\boxed{\Big[-6 \ ; \ -4\Big]}$