7+5^1/2/7-5^1/2-7-5^1/2/7+5^1/2=a+7 /11 5b find value of a and b

Which equations represents circles that have a diameter of 12 units and a center that lies on the y-axis? check all that apply

The general form of the quetion of a circle is ax^2+by^2+cx+dy+e=0 where a=b=0 if the circle has a radius of three units and the center lies on the y axis which set of values of a, b, c, d, and e might correspond to the circle

Which expression will have the same sum as 3_8 + 1/4?