Question

Решить неравенство 2^(2x+1) + 2^(x+2) > 16

Answer 1

$2^{2x+1}+2^{x+2}\ \textgreater \ 16\\2^{2x}*2^1+2^x*2^2\ \textgreater \ 16\\2*2^{2x}+4*2^x\ \textgreater \ 16|:2\\2^{2x}+2*2^x\ \textgreater \ 8\\a=2^x\\a^2+2a-8\ \textgreater \ 0\\ \left \{ {{a_1*a_2=-8} \atop {a_1+a_2=-2}} \right.=\ \textgreater \ a_1=2;\; \; \; a_2=-4\\\\(a-2)(a+4)\ \textgreater \ 0$
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__________-4_____________2___________

$2^x\ \textless \ -4\\x\in\varnothing \\\\2^x\ \textgreater \ 2\\2^x\ \textgreater \ 2^1\; \; (2\ \textgreater \ 1)\\x\ \textgreater \ 1\\x\in(1;+\infty)$