Solve the system of equations
x + y + z = 6
x + 2y + 3z = 14
x + 4y + 7z = 30
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\textbf{Solve the system of equations:}
\[
\begin{aligned}
(1)\quad & x + y + z = 6 \\
(2)\quad & x + 2y + 3z = 14 \\
(3)\quad & x + 4y + 7z = 30
\end{aligned}
\]
\textbf{Step 1: Subtract equation (1) from equations (2) and (3)}
Subtracting (1) from (2):
\[
(x + 2y + 3z) - (x + y + z) = 14 - 6
\Rightarrow y + 2z = 8 \tag{4}
\]
Subtracting (1) from (3):
\[
(x + 4y + 7z) - (x + y + z) = 30 - 6
\Rightarrow 3y + 6z = 24 \tag{5}
\]
\textbf{Step 2: Solve equations (4) and (5)}
Equation (5) simplifies:
\[
3y + 6z = 24 \Rightarrow y + 2z = 8 \tag{5'}
\]
Now, equations (4) and (5') are the same:
\[
y + 2z = 8
\]
So, the system has infinitely many solutions. Let \( z = t \), a parameter.
Then,
\[
y = 8 - 2t
\]
\textbf{Step 3: Substitute into equation (1)}
Using equation (1): \( x + y + z = 6 \)
\[
x + (8 - 2t) + t = 6
\Rightarrow x + 8 - t = 6
\Rightarrow x = -2 + t
\]
\textbf{Final Answer:} (in terms of parameter \( t \))
\[
\boxed{
\begin{aligned}
x &= -2 + t \\
y &= 8 - 2t \\
z &= t
\end{aligned}
}
\quad \text{where } t \in \mathbb{R}
\]
\end{document}