3x$x^2-3x+2$-x^2$9x^2-4$

Expanding the first term:
3x$x^2$ - 3x$3x$ + 3x$2$

= 3x^3 - 9x^2 + 6x

Expanding the second term:
-x^2$9x^2$ + x^2$4$

= -9x^4 + 4x^2

Combining the two terms:
3x^3 - 9x^2 + 6x - 9x^4 + 4x^2

Rearranging the terms:
-9x^4 + 3x^3 - 5x^2 + 6x

Therefore, the simplified expression is:
-9x^4 + 3x^3 - 5x^2 + 6x