If z varies inversely as w and z=40 when w=0.1, find z when w=20

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

I’m really confused and need your assist me with this question i’ve never been taught

Astudent was asked to find the square of 7x+3. the student quickly wrote (7x+3)^3= 49x^2+9. identify the student's error and provide the correct answer.