[tex]\bf 1000^{log_{10}(x)}\qquad 1000=10^3\\\\
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{{ a}}^{log_{{ a}}x}=x\impliedby \textit{using the log cancellation}\\\\\\
and\qquad log_{{ a}}\left( x^{{ b}} \right)\implies {{ b}}\cdot log_{{ a}}(x)\\\\
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(10^3)^{log_{10}(x)}\implies 10^{3log_{10}(x)}\implies 10^{log_{10}(x^3)}\implies x^3[/tex]