Final answer:
To simplify an expression, you combine like terms. In the case of 4y²-3y³-7y²+5y³, you combine 4y² with -7y² and -3y³ with 5y³ to get -3y² and 2y³, respectively. Therefore, the simplified expression is 2y³ - 3y².
Step-by-step explanation:
To simplify the expression 4y²-3y³-7y²+5y³ and combine like terms, you first put together the terms that have the same variable and exponent. That would be 4y² and -7y² for y²; -3y³ and 5y³ for y³.
Next, you perform the operations for each set of like terms. That is, 4y² - 7y² equals -3y² and -3y³ + 5y³ equals 2y³.
Therefore, the simplified expression is 2y³ - 3y².
Learn more about Simplifying Expressions