simplfy (9x^2 -6x +2)-(x^2 +4x -39)

To simplify the expression \((9x^2 - 6x + 2) - (x^2 + 4x - 39)\), first distribute the negative sign through the second set of parentheses:

\[
9x^2 - 6x + 2 - x^2 - 4x + 39
\]

Now, combine like terms:

1. Combine the \(x^2\) terms:
\(9x^2 - x^2 = 8x^2\)

2. Combine the \(x\) terms:
\(-6x - 4x = -10x\)

3. Combine the constant terms:
\(2 + 39 = 41\)

Putting it all together, we have:

\[
8x^2 - 10x + 41
\]

So, the simplified expression is:

\[
\boxed{8x^2 - 10x + 41}
\]