For a combination of lenses, the power of each lens is added to get the resultant power. P = P1 + P2. WHY?
The power of P(1,2) with respect to the circle x2+y2+4x+2y+3 = 0 is double the power of P with respect to x2+y2+2x+y+k = 0 then the value of k is
Verify that : X to the power 3 + y to the power 3 + z to the power 3-3xyz=1\2(x+y+z)[(x-y)to the power 2+(y-z) to the power 2+(z-x) to the power 2