In the expression \(3x - 4 + x + 7\), we need to identify pairs of like terms. Like terms are terms that have the same variable raised to the same power.
Let's look at the terms in the expression:
- \(3x\) (a term with \(x\))
- \(-4\) (a constant)
- \(x\) (a term with \(x\))
- \(7\) (a constant)
Now let's check the options:
- x and -7: Not a pair of like terms (one is a variable and the other is a constant).
- 3x and x: This is a pair of like terms (both have the variable \(x\)).
- 3x and -4: Not a pair of like terms (one has variable \(x\) and the other is a constant).
- -4 and 7: Not a pair of like terms (both are constants, but they are not like in the sense of having the same variable).
Thus, the only pair of like terms is 3x and x.