Final answer:
The commutative property of addition justifies the equivalence of the two expressions in the equation.
Step-by-step explanation:
The property of operations that can be used to justify that the two expressions in the equation are equivalent is the commutative property of addition. This property states that the order of the addends does not affect the sum. In this equation, the terms 2.8x² and 4x are being added, and the commutative property allows us to rearrange them without changing the result.
So, 2.8x² + 4x can be written as 4x + 2.8x², which means the two expressions are equivalent.
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