`-9-a=b`
`a^2-6a-9=b`
IF the ordered pair (a,b) satisfies the system of equations above, what is one possible value of a?

Answer

To solve the system of equations given by:

1. \(-9 - a = b\)
2. \(a^2 - 6a - 9 = b\)

we will substitute the expression for \(b\) from the first equation into the second equation.

### Step-by-step Solution:

**Step 1:** Substitute \(b\) from the first equation into the second equation.

From equation 1, we have:
\[ b = -9 - a \]

Now, substitute this value of \(b\) into equation 2:
\[ a^2 - 6a - 9 = -9 - a \]

**Step 2:** Simplify the equation.

Now, we can simplify the equation:
\[ a^2 - 6a - 9 + 9 + a = 0 \]
This simplifies to:
\[ a^2 - 6a + a = 0 \]
\[ a^2 - 5a = 0 \]

**Step 3:** Factor the equation.

We can factor the left-hand side:
\[ a(a - 5) = 0 \]

**Step 4:** Set each factor to zero.

Now we set each factor equal to zero:
1. \(a = 0\)
2. \(a - 5 = 0 \Rightarrow a = 5\)

Thus, the possible values of \(a\) are \(0\) and \(5\).

### Conclusion:

One possible value of \(a\) is \(0\) (or \(5\) as well).

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