Question 800476
P(-1,1) Q(1,3)

center on x axis

so y co ordinate of center =0

let the center = O(x,0)

l(OP) =l(OQ)

(x+1)^2+(0-1)^2= (x-1)^2+(0-3)^2

x^2+2x+1+1 =x^2-2x+1+9

4x=8
x=2

The center = (2,0)

Now you can complete