Question

How do you find the vertex and roots of x^2-17x+72 ?

Answer 1

To find the roots, solve by factoring: x^2 - 17x + 72 = 0. I use the Diagonal Sum Method with a = 1. Both roots are positive. Compose factor pair of c = 72. Proceeding: (1, 72)...(8, 9). This last sum is 17 = -b. Then the 2 real roots (or x-intercepts) are 8 and 9.
x-coordinate of the parabola axis = -b/2a
y of vertex: Replace in the trinomial x by the above value.