7x²-5x+3 и 7x²-5

These are both quadratic expressions.

The first expression is 7x^2 - 5x + 3. This expression cannot be simplified any further. If you need to solve for x, you can use the quadratic formula or factor it if possible.

The second expression is 7x^2 - 5. This expression is already in its simplified form. There is no need for further simplification.