(1)
(2x)²+3x+3<0
∵(2x)²+3x+3=(2x+3/4)²+39/16>0
∴(2x)²+3x+3<0无解
即不等式解集是空集
(2)
2x+3-x²≥0
x²-2x-3≤0
(x-3)(x+1)≤0
-1≤x≤3