Question

Giải bất phương trình

a) x³ - 6x² + 5x + 12 >0

b) \(\frac{5x\left(2x+1\right)\left(5-x\right)}{\left(x+3\right)\left(3x-4\right)}>0\)

c) \(\frac{1}{2-3}>\frac{2}{1+4x}\)

d) \(\frac{1}{x}+\frac{2}{x+2}< \frac{3}{x+1}\)

e) 3x³ - 14x² + 20x >8

f) x⁵ - x⁴ + x³ - x² + x - 1<0

g) (x - 1)(x - 3)(x + 5)(x + 7)<297

h) x⁴ - 2x³ + x >132

Answer 1

\(x^3-6x^2+5x+12>0\\ < =>\left(x^3-5x-x+5x\right)+12>0\\ < =>\left[\left(x^3-x\right)-\left(5x-5x\right)\right]+12>0\\ < =>x^2+12>0\\ < =>x^2>-12\\ =>x\in R\\ BPTcóvôsốnghiem\)