a, Đkxđ:
$\frac{2x-5}{3}$ ≥ 0
mà 3>0
=> 2x-5 ≥ 0
=> x≥$\frac{5}{2}$
b, đkxđ:
x²-16≥0
=> x≥-4 hoặc x≥4
mà 4>-4
=> x ≥-4
c,đkxđ:
$\left \{ {{\frac{-7}{-3x}≥0} \atop {-3x\neq0 }} \right.$
=> $\left \{ {{3x≥0} \atop {x\neq0}} \right.$
=> x>0
d, đkxđ
$\left \{ {{\frac{2+x}{5-x}≥0} \atop {5-x\neq0}} \right.$
=>$\left \{ {{2+x≥0} \atop {x\neq5}} \right.$
=>$\left \{ {{x≥-2} \atop {x\neq5}} \right.$
e, đkxđ:
x²+2x-3>0
=>(x+1)²>2
=> x+1>√2
=> x>√2 - 1
f, đkxđ :
$\left \{ {{2x-1≥0} \atop {x-2\neq0}} \right.$
=>$\left \{ {{x≥1/2} \atop {x\neq2}} \right.$
