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The ordered pair $$(a, b)$$, for which the system of linear equations
$$3x - 2y + z = b$$
$$5x - 8y + 9z = 3$$
$$2x + y + az = -1$$
has no solution, is
We need to find the ordered pair $$(a, b)$$ for which the system has no solution:
$$3x - 2y + z = b$$
$$5x - 8y + 9z = 3$$
$$2x + y + az = -1$$
Since the system has no solution, the determinant of the coefficient matrix must be zero. Thus
$$D = \begin{vmatrix} 3 & -2 & 1 \\ 5 & -8 & 9 \\ 2 & 1 & a \end{vmatrix}$$
$$= 3(-8a - 9) + 2(5a - 18) + 1(5 + 16)$$
$$= -24a - 27 + 10a - 36 + 21$$
$$= -14a - 42$$
Setting $$D = 0$$ gives $$-14a - 42 = 0$$, which implies $$a = -3$$.
Next, for the system to have no solution rather than infinitely many, at least one of $$D_x, D_y, D_z$$ must be non-zero. Substituting $$a = -3$$ into the determinant $$D_x$$ formed by replacing the first column of the coefficient matrix with the constants, we have
$$D_x = \begin{vmatrix} b & -2 & 1 \\ 3 & -8 & 9 \\ -1 & 1 & -3 \end{vmatrix}$$
$$= b(24 - 9) + 2(-9 + 9) + 1(3 - 8)$$
$$= 15b + 0 - 5 = 15b - 5$$
Since $$D_x \neq 0$$ is required, it follows that $$b \neq \frac{1}{3}$$.
From the given options with $$a = -3$$, namely Option B $$(-3, \frac{1}{3})$$ and Option C $$(-3, -\frac{1}{3})$$, only $$b = -\frac{1}{3}$$ satisfies this condition. Substituting $$b = -\frac{1}{3}$$ into $$D_x$$ yields
$$D_x = 15\bigl(-\tfrac{1}{3}\bigr) - 5 = -5 - 5 = -10 \neq 0$$ ✓
Therefore, the ordered pair is $$\left(-3, -\frac{1}{3}\right)$$.
The correct answer is Option C.
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