Question

Решите неравенства!! -4х^2+13х+12>_0 Х^2-4х-5<0

Answer 1

1)$-4 x^{2} +13x+12 \geq 0$
$4 x^{2} -13x-12 \leq 0$
$D:169-4*4*-12= \sqrt{361} =19$
$x_{1} = \frac{13-9}{2*4} = \frac{1}{2}$
$x_{2} = \frac{13+9}{2*4} = \frac{11}{4}$
Ответ: [$\frac{1}{2} ; \frac{11}{4}$]
2)$x^{2} -4x-5<0$
$D:16-4*1-5= \sqrt{36} =6$
$x_{1} = \frac{4-6}{2} =-1$
$x_{2} = \frac{4+6}{2} =5$
Ответ:(-1;5)