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Solve the system of equations

                        x + y + z = 6

                        x + 2y + 3z = 14

                        x + 4y + 7z = 30

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\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}
 

Posted by

Saumya Singh

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