Question 2: R= 12/5

Solution: According to Pythagorean theorem, we know that AB=5, because the circle is tangent to AB, and the radius of the circle is the high line on the hypotenuse AB of triangle ABC. Using the equal area method, that is, 3*4=5*x, the solution is: x= 12/5.

Question 3: m= plus or minus 2, and the value range of M is greater than -2 and less than +2.

Solution: Because the ordinate of the center of the circle is 0, the center of the circle is on the X axis, the radius is 2, and it is tangent to the Y axis, so the value of m is plus or minus 2. If the circle intersects the Y axis, the distance from the center of the circle to the Y axis must be less than 2, so the range of m is greater than -2 and less than +2.