Đáp án:
Giải thích các bước giải:
a)
`5x-6>0`
`<=> 5x>6`
`<=> x>6/5`
$\rm S=\{x \ | \ x>\dfrac{6}{5}\}$
b)
`-12-4x <=0`
`<=> -4x <= 12`
`<=> x >= 3`
$\rm S=\{x \ | \ x \geq 12\}$
c)
`4.(1-2x)-2.(x^2-6) < x-2x^2`
`<=> 4-8x-2x^2+12 < x-2x^2`
`<=> -2x^2+2x^2-8x-x < -12-4`
`<=> -9x <= -16`
`<=> x >= 16/9`
$\rm S=\{x \ | \ x \geq -\dfrac{16}{9}\}$
d)
`(x+1)(x-2) >= x^2-3`
`<=> x^2-2x+x-2 >= x^2-3`
`<=> x^2-x-2 >= x^2-3`
`<=> x^2-x^2-x >= -3+2`
`<=> -x >= -1`
`<=> x<= 1`
$\rm S=\{x \ | \ x \leq 1\}$
e)
`(x+4)/5 - (x-2)/2 >=3`
`<=> (2.(x+4)-5.(x-2))/10 >= 3`
`<=> 2x+8-5x+10 >= 30`
`<=> -3x >= 30-10-8`
`<=> -3x >= 12`
`<=> x <= -4`
$\rm S=\{x \ | \ x \leq -4\}$
