Advertisements (Quảng cáo)
Giải các bất phương trình sau
a) \(3{x^2} – 7x + 4 \le 0\)
b) \({x^2} – 3x + 5 > 0\)
c) \({x^2} + 4 \ge \left| {3x + 2} \right| – 7x\)
e) \({{2x + 3} \over {{x^2} + x – 12}} \le {1 \over 2}\)
g) \({{{x^4} – 3{x^3} + 2{x^2}} \over {{x^2} – x – 30}} > 0\)
Gợi ý làm bài
a) \(\left[ {1;{4 \over 3}} \right]\)
Advertisements (Quảng cáo)
b) \(( – \infty ; + \infty )\)
c) \(\left( { – \infty ;{{4 – \sqrt 2 } \over 2}} \right] \cup \left[ {{{5 + \sqrt 3 } \over 2}; + \infty } \right)\)
d) \(\left( { – \infty ;{{ – 5 – \sqrt {19} } \over 3}} \right) \cup \left( {{{4 + \sqrt {19} } \over 3}; + \infty } \right)\)
e) \(( – \infty ; – 4) \cup ( – 3;3) \cup (6; + \infty )\)
g) \(( – \infty ; – 5) \cup (1;2) \cup (6; + \infty )\)