GEOMETRY CLASS PLEASE HELP 15 POINTS

especially # 20. please

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

Asystem of linear equations contains two equations with the same slope. select all of the correct statements. i a. the system may have two solutions. - b. the system may have infinitely many solutions. c. the system may have one solution. o d. the system may have no solution. submit

Evaluate each expression. determine if the final simplified form of the expression is positive or negative -42 (-4)2 42