Find the point to which the origin be shifted after a translation, so that the equation x2+y2−4x−8y+3=0will have no first degree terms.
Let the origin O be shifted to a point O' (h, k).
Let the new coordinates of P(x, y) be P(x', y').
Then, x′=x−h⇒ x = x' +h
And, y' = y - k ⇒y = y' + k
So, the new equation becomes :
(x′+h2)+(y′+k2)−4(x′+h)−8(y′+k)+3=0⇒(x′2+h2+2x′h)+(y′2+k2+2y′k)−4(x′+h)−8(y′+k)+3=0⇒x′2+y′2+(2h−4)x′+(2k−8)y′+(h2+k2−4h−8k+3)=0
Since we are required to get an equation free from first degree terms, so we have :
(2h−4=0 and 2k−8=0)⇒(2h=4 and 2k=8)⇒(h=2 and k=4)
Hence, the origin O should be shifted to the point O' (2, 4)