Answer:
**1. Sequences:**
**1.1) x/y²; -x²/y; x³;...**
- This sequence is neither arithmetic nor geometric. The terms involve different powers of \(x\) and \(y\), and there's no consistent common difference or ratio.
**1.2) tan 30°; tan 45°; tan 60°**
- This sequence is neither arithmetic nor geometric. The terms involve tangent values of different angles, and there's no consistent common difference or ratio.
**2. Arithmetic Sequence:**
Given the arithmetic sequence \(3x-1; 2x+3; 2x-1\),
**2.1) Find the value of x:**
- Identify the common difference between terms.
- \((2x+3) - (3x-1) = -x + 4\)
- Set \( -x + 4 = 2x - 1\), solve for \(x\).
**2.2) Find the sequence:**
- Once \(x\) is found, substitute it back into the original sequence.
**2.3) Find which term is -57:**
- Plug the value of \(x\) into the sequence formula, and solve for \(n\) when \(3x-1 = -57\).
