The graph of a quadratic function contains the points
(1, 9), (0, 0), and (–1, 9). Shawn thinks the function
f(x) = x2 was vertically stretched by a factor of 9. Brielle thinks the function f(x) = x2 was horizontally shrunk by a factor of 3. Determine who is correct and explain why.

Both Shawn and Brielle are correct. The function that represents a vertical stretch by a factor of 9 is f(x)=9×2.The function that represents a horizontal shrink by a factor of 3 is:   f(x)=(3x)2, which is equal to f(x)=9×2.

Additionally, if you wanted to verify that the given points are on the graph of both functions, you could substitute them into the functions to get true statements.