Question

a^2-64b^2/a^2*a/a-8b при a=√45, b=√405

Answer 1

$\frac{a^2-64b^2}{a^2} * \frac{a}{a-8b} = \frac{(a+8b)(a-8b)}{a^2} * \frac{a}{a-8b} =\frac{a+8b}{a} =$

$= \frac{ \sqrt{45}+8 \sqrt{405} }{ \sqrt{45} } = \frac{ \sqrt{9*5}+8 \sqrt{81*5} }{ \sqrt{9*5} } = \frac{3 \sqrt{5}+8*9 \sqrt{5} }{3 \sqrt{5} } = \frac{3 \sqrt{5}+72 \sqrt{5} }{3 \sqrt{5} } = \frac{75 \sqrt{5} }{3 \sqrt{5} } =25$