Simultaneous Equations
1. State the problem: Solve the simultaneous equations $3x^2 - xy = 0$ and $2y - 5x = 1$.
2. Isolate $y$ from the linear equation.
$$2y - 5x = 1$$
$$2y = 5x + 1$$
$$y = \frac{5x + 1}{2}$$
3. Substitute the expression for $y$ into the quadratic equation $3x^2 - xy = 0$.
$$3x^2 - x\left(\frac{5x + 1}{2}\right) = 0$$
Multiply both sides by 2 to clear the denominator.
$$6x^2 - x(5x + 1) = 0$$
Expand and simplify.
$$6x^2 - 5x^2 - x = 0$$
$$x^2 - x = 0$$
Factor the left-hand side.
$$x(x - 1) = 0$$
Hence $x = 0$ or $x = 1$.
4. Substitute each $x$ value back to find $y$.
If $x = 0$ then
$$y = \frac{5\cdot 0 + 1}{2} = \frac{1}{2}$$
If $x = 1$ then
$$y = \frac{5\cdot 1 + 1}{2} = \frac{6}{2} = 3$$
5. Final answer: The solutions are
$$ (x,y) = (0, \tfrac{1}{2}),\; (1, 3) $$