数学疑问

求救~拍谢..

1. Write the equation of the line with gradient m and passes the point P(0,18). Show
that this line is the tangent to the circle with centre C(4,6) and the
radius 10 units with m satisfies the equation 21m^2 -24m -11 = 0.

2. A point moves such that its distance from the point A(-2,3) is twice its distance from the point B(1,-1). Show that the locus of this point is a circle and state its centre and radius.

第一题不懂他的show是什么意思..
第二题的又怎样叫show?!

第一个是要你prove 那条线form一个直线, then 那个线 跟那个=tangent~ 像这样~

可以用这个方法~
1。算cp的gradient,然后算那个直线的equation,再prove他们两个线的gradient乘在一起等于 -1

不好意思现在才看到你的题目~

至于第二个呢，可以这样子做~