几道解不等式 1.X²-2X-3>0 2.X²+3X-4≤0 3.3X²-7X+2<0 4.-X²-X+20>0

问题描述:

几道解不等式 1.X²-2X-3>0 2.X²+3X-4≤0 3.3X²-7X+2<0 4.-X²-X+20>0

1.X²-2X-3>0
(x-3)(x+1)>0
x>3 or x