Final answer:
The y-intercept of the quadratic function f(x) = (x-10)(x+2) is -20.
Step-by-step explanation:
The y-intercept of a quadratic function is the point where the graph of the function crosses the y-axis. To find the y-intercept of the quadratic function f(x) = (x-10)(x+2), we set x=0 and solve for y. Plugging in x=0, we get y = (0-10)(0+2) = (-10)(2) = -20. Therefore, the y-intercept of the quadratic function is -20.