Question

очень очень срочна,помогите

Answer 1

$3)\; \; 4^{x^2+5x-12}\geq 16\\\\4^{x^2+5x-12}\geq 4^2\\\\x^2+5x-12\geq 2\\\\x^2+5x-14\geq 0\\\\(x+7)(x-2)\geq 0\qquad +++[-7\, ]---[\, 2\, ]+++\\\\x\in (-\infty -7\, ]\cup [\, 2,+\infty )\\\\4)\; \; 6^{x+1}+6^{x+2}<252\\\\6^{x}\cdot (6+6^2)<252\\\\6^{x}<6\\\\x<1\; \; \to \; \; x\in (-\infty ,1)$

$5)\; \; (\frac{3}{5})^{3x-13}\leq \frac{9}{25}\\\\(\frac{3}{5})^{3x-13}\leq (\frac{3}{5})^2\\\\3x-13\geq 2\\\\3x\geq 15\\\\x\geq 5\; \; \to \; \; x\in [\, 5,+\infty )$