Subjects algebra

Simultaneous Equations A9B250

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1. The problem is to solve a system of simultaneous linear equations. 2. The general form of simultaneous linear equations is: $$\begin{cases} ax + by = c \\ dx + ey = f \end{cases}$$ where $a,b,c,d,e,f$ are constants. 3. To solve, we can use substitution or elimination methods. Here, we use elimination: 4. Multiply the first equation by $e$ and the second by $b$ to align coefficients of $y$: $$e(ax + by) = ec \Rightarrow aex + bey = ec$$ $$b(dx + ey) = bf \Rightarrow bdx + bey = bf$$ 5. Subtract the second from the first: $$aex + bey - (bdx + bey) = ec - bf$$ $$aex - bdx = ec - bf$$ 6. Factor $x$: $$x(ae - bd) = ec - bf$$ 7. Solve for $x$: $$x = \frac{ec - bf}{ae - bd}$$ 8. Substitute $x$ back into one of the original equations to find $y$. This method finds the unique solution $(x,y)$ if $ae - bd \neq 0$. Final answer: $$x = \frac{ec - bf}{ae - bd}, \quad y = \frac{af - dc}{ae - bd}$$ where $y$ is found similarly by elimination.