Final answer:
To write a quadratic function that has been transformed by a stretch factor of 3 and a vertical shift down 1 unit, start with the basic quadratic function y = x^2. Multiply the x term by 3 to stretch the function and subtract 1 to shift it down.
Step-by-step explanation:
To write a quadratic function that has been transformed by a stretch factor of 3 and a vertical shift down 1 unit, we can start with a basic quadratic function like y = x^2. To stretch the function by a factor of 3, we multiply the x term by 3, resulting in y = (3x)^2. To shift the function down 1 unit, we subtract 1 from the entire function, giving us the final quadratic function: y = (3x)^2 - 1.