(2x 2 −4)−(−x 2 +3x−6)

Sure, let's solve this step by step:

Given expression is: (2x^2 - 4) - (-x^2 + 3x - 6)

Step 1: Remove the brackets. The minus sign before the second bracket will change the signs of the terms inside the bracket.

So, the expression becomes: 2x^2 - 4 + x^2 - 3x + 6

Step 2: Combine like terms.

The expression becomes: (2x^2 + x^2) - 3x + (6 - 4)

Step 3: Simplify the expression.

The expression becomes: 3x^2 - 3x + 2

So, the simplified form of the given expression is 3x^2 - 3x + 2.