Final answer:
The expressions that can be simplified by combining like terms are B) z + 2z - 7, which simplifies to 3z - 7, and E) 5x + 6y - 6x, which simplifies to -x + 6y, assuming 'бу' is a typographical error and should be '6y'. The other expressions cannot be simplified by combining like terms.
Step-by-step explanation:
To determine which of the following expressions can be simplified by combining like terms, we'll go through each option one by one:
- A) 3x + x^2: We cannot combine these terms because they are not like terms; x and x^2 represent different powers of x.
- B) z + 2z - 7: The terms z and 2z can be combined because they are like terms. The simplified expression is 3z - 7.
- C) 4xy - x - y: These terms cannot be combined because each term contains different variables or different numbers of variables.
- D) 9 - x: This expression cannot be simplified further because there are no like terms to combine.
- E) 5x + бу - 6x: Assuming 'бу' is a typographical error and should read '6y', we can combine the like terms 5x and -6x. The simplified expression is -x + 6y.
To check if the simplified expressions are reasonable, we ensure that only like terms with the same variable and power are combined and that no mathematical errors were made in the process.