Question

Помогите решить :

а²-49b²/a² × a/a+7b

При а =√245 , b = √125

Answer 1

$\\\frac{a^2-49b^2}{a^2} * \frac{a}{a+7b} = \frac{(a-7b)(a+7b)}{a^2} * \frac{a}{a+7b} = \frac{a-7b}{a}$
$\\\frac{\sqrt{245} - 7\sqrt{125}}{\sqrt{245}} = \frac{\sqrt{5}(\sqrt{49} - 7\sqrt{25})}{\sqrt{5*49}} = \\ \\ = \frac{7-7*5}{7} = \frac{7*(1-5)}{7} = 1-5 = -4$