Quadratic functions

Question

By graphing the quadratic function f(x)=x²-2x+4 find the domain and range 

Answer 1

The vertex of the parabola is found by putting the equation in quadratic form which is: f(x) = ax^2+bx+c . So the vertex is (h,k) and h=-b/2a. So since a=1 and b=-2 the vertex is (1,3)   Since a=1 and a positive value means it opens upward. So the y value of the vertex is the lowest point on the range which is 3. The highest point is infinity since it goes down - forever. So the range is (3,∞).  The domain of the quadratic is (-∞,∞).