To solve the quadratic equation $y = x^2 - 4x$, we can express it in a more standard form by completing the square or using the quadratic formula.

Step 1: Write the equation in standard form

The given equation is: $y = x^2 - 4x$ To solve for $x$ when $y = 0$, set the equation equal to zero: $x^2 - 4x = 0$

Step 2: Factor the quadratic expression

We can factor the quadratic expression: $x(x - 4) = 0$

Step 3: Solve for $x$

Now, set each factor equal to zero:

1. $x = 0$
2. $x - 4 = 0 \implies x = 4$

Thus, the solutions are: $x = 0 \quad \text{or} \quad x = 4$

Final Answer:

The solutions to the equation $y = x^2 - 4x$ when $y = 0$ are: $x = 0 \quad \text{or} \quad x = 4$

Would you like further explanation on any step, or do you have any other questions?

Here are 5 related questions:

1. How do you complete the square to solve a quadratic equation?
2. How do you apply the quadratic formula to solve for $x$?
3. What is the vertex of the quadratic equation $y = x^2 - 4x$?
4. What happens to the equation if we have a different constant, like $y = x^2 - 4x + 5$?
5. Can the quadratic equation $x^2 - 4x = 0$ have complex solutions?

Tip: To check your solutions, you can substitute $x = 0$ and $x = 4$ back into the original equation to verify they satisfy $y = 0$.