Question

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Answer 1

$frac{a^2-16b^2}{4ab}:( frac{1}{4b}- frac{1}{a} )= frac{a^2-16b^2}{4ab}: frac{a-4b}{4ab} = frac{(a-4b)(a+4b)}{4ab}* frac{4ab}{a-4b} = a+4b$

при $a=4 frac{9}{13}; b=6 frac{1}{13}$

$a+4b=4 frac{9}{13}+4*6 frac{1}{13}= frac{61}{13} +4* frac{79}{13}= frac{61+316}{13} =frac{377}{13} =29$