The equation of the ellipse is 9(x+y−2)2+16(x−y)2=144……(1)
Differentiating ( 1 ) with respect to x, treating y as
constant, wega, 18(x+y−2)+32(x−y)=0….(2)
Differentiating( 1 ) with respcctioy.trating xasconstnat.
weget, 18(x+y−2)−32(x−y)=0….(3)
Solving ( 2 ) and ( 3 ), we get the coordinates of the
centre (1,1)