Question

Помогите с алгеброй.

Answer 1

Ответ:

6.75

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Answer 2

$frac{1}{k - 7} - frac{9}{k + 7} = frac{1}{k - 7} times frac{9}{k + 7} \ frac{k + 7 - 9k + 63}{(k - 7)(k +7)} = frac{9}{(k - 7)(k + 7)} \ frac{70 - 8k}{(k + 7)(k - 7)} - frac{9}{(k - 7)(k + 7)} = 0 \ frac{61 - 8k}{(k +7 )(k - 7)} = 0 \ 61 - 8k = 0 \ - 8k = - 61 \ k = 7 frac{5}{8}$

Ответ: 7 5/8,да и ещё k≠±7