Подстановка условия
[src]
log(5 - x)/log(4) при x = -1
log(5 - x)
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log(4)
$$\frac{\log{\left(- x + 5 \right)}}{\log{\left(4 \right)}}$$
log(5 - x)
----------
log(4)
$$\frac{\log{\left(- x + 5 \right)}}{\log{\left(4 \right)}}$$
$$x = -1$$
log(5 - (-1))
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log(4)
$$\frac{\log{\left(- (-1) + 5 \right)}}{\log{\left(4 \right)}}$$
log(5 - -1)
-----------
log(4)
$$\frac{\log{\left(\left(-1\right) \left(-1\right) + 5 \right)}}{\log{\left(4 \right)}}$$
$$\frac{\log{\left(6 \right)}}{\log{\left(4 \right)}}$$