Answer
$-2,-1,\frac{1}{2},1$
Work Step by Step
The possible rational zeros are $\pm1,\pm1/2,\pm2$
Use synthetic division or the remainder theorem to test each value and we can confirm two zeros as $-1,+1$
$P(1)=2+3-4-3+2=0$
$P(-1)=2-3-4+3+2=0$
Again, use synthetic division to reduce P into a quadratic form as
$P(x)=(x+1)(x-1)(2x^2+3x-2)=(x-1)(x+1)(2x-1)(x+2)$
so the zeros are $-2,-1,1/2,1$