Solve the system of linear equations by graphing y=2x+5 and y=1/2x-1

The graph of y = ax^2 + bx + c is a parabola that opens up and has a vertex at (0, 5). what is the solution set of the related equation 0 = ax%2 + bx + c?

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?

The triangles in the diagram are congruent. if mzf = 40°, mza = 80°, and mzg = 60°, what is mzb?