13 18 O-8+6i 15. Find the vertex for y = 41 - 82 - 12. use - (17 - 4ac) from the quadratic formula & = -b+ vb - 4ac 4a O (1, 16) O (16, -1) O (-16, -1) O (-1,0) O (1,-16) 16. Find the solution (s) to the systems of equations algebraically. Select all that apply