What is the number if half of the digits are twos

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

Factor the polynomial. b^2 + 4b + 4

Astudent draws two parabolas on graph paper. both parabolas cross the x-axis at (–4, 0) and (6, 0). the y-intercept of the first parabola is (0, –12). the y-intercept of the second parabola is (0, –24). what is the positive difference between the a values for the two functions that describe the parabolas? write your answer as a decimal rounded to the nearest tenth