Step 1: Given the quadratic polynomial:
We are given the quadratic polynomial \( (\alpha - 1)x^2 + \alpha x + 1 \), and it is stated that one of the zeroes of this polynomial is \( -3 \). This means that \( x = -3 \) is a root of the equation. Therefore, we can substitute \( x = -3 \) into the polynomial and set it equal to zero to find the value of \( \alpha \).
Step 2: Substitute \( x = -3 \) into the polynomial:
Substituting \( x = -3 \) into the equation \( (\alpha - 1)x^2 + \alpha x + 1 = 0 \), we get:
\[
(\alpha - 1)(-3)^2 + \alpha(-3) + 1 = 0
\]
Simplifying the terms:
\[
(\alpha - 1)(9) - 3\alpha + 1 = 0
\]
\[
9(\alpha - 1) - 3\alpha + 1 = 0
\]
Distribute the 9:
\[
9\alpha - 9 - 3\alpha + 1 = 0
\]
Now combine like terms:
\[
9\alpha - 3\alpha - 9 + 1 = 0
\]
\[
6\alpha - 8 = 0
\]
Add 8 to both sides:
\[
6\alpha = 8
\]
Now, divide both sides by 6:
\[
\alpha = \frac{8}{6} = \frac{4}{3}
\]
Step 3: Conclusion:
The value of \( \alpha \) is \( \frac{4}{3} \).