Simplify (14x2−3x+2.25)+(0.75x2+2x−14)

To simplify the expression \((14x^2 - 3x + 2.25) + (0.75x^2 + 2x - 14)\), we need to combine like terms.

1. Combine the \(x^2\) terms:
\[
14x^2 + 0.75x^2 = 14.75x^2
\]

2. Combine the \(x\) terms:
\[
-3x + 2x = -1x \quad \text{or simply} \quad -x
\]

3. Combine the constant terms:
\[
2.25 - 14 = -11.75
\]

Now, putting all the combined terms together, we have:
\[
14.75x^2 - x - 11.75
\]

Therefore, the sum of the polynomials is:
\[
\boxed{14.75x^2 - x - 11.75}
\]