Simplify:
`2-3z^(2)+5yz+7y^(2)-8+z^(2)-6yz-9y^(2)+1-2z^(2)-2yz-y^(2)`

Answer

To simplify the expression \( 2 - 3z^2 + 5yz + 7y^2 - 8 + z^2 - 6yz - 9y^2 + 1 - 2z^2 - 2yz - y^2 \), we will follow these steps:

### Step 1: Group the Like Terms
We will group the constants, \( z^2 \) terms, \( yz \) terms, and \( y^2 \) terms separately.

1. **Constants**: \( 2, -8, +1 \)
2. **\( z^2 \) terms**: \( -3z^2, +z^2, -2z^2 \)
3. **\( yz \) terms**: \( +5yz, -6yz, -2yz \)
4. **\( y^2 \) terms**: \( +7y^2, -9y^2, -y^2 \)

### Step 2: Simplify Each Group
Now we will simplify each group.

1. **Constants**:
\[ 2 - 8 + 1 = -6 + 1 = -5 \]

2. **\( z^2 \) terms**:
\[ -3z^2 + z^2 - 2z^2 = (-3 + 1 - 2)z^2 = -4z^2 \]

3. **\( yz \) terms**:
\[ 5yz - 6yz - 2yz = (5 - 6 - 2)yz = -3yz \]

4. **\( y^2 \) terms**:
\[ 7y^2 - 9y^2 - y^2 = (7 - 9 - 1)y^2 = -3y^2 \]

### Step 3: Combine All the Simplified Terms
Now we combine all the simplified terms:
\[ -5 - 4z^2 - 3yz - 3y^2 \]

### Final Answer
Thus, the simplified expression is:
\[ -4z^2 - 3yz - 3y^2 - 5 \]