what is equation for translation of (x-2)^2 + (y+1)^2=16 by 3 units left and 5 units up? the answer is (x-5)^2 + (y +6)^2=16. Why not (x+1)^2 +(y-4)^2=16. thought move to left is positive and up is negative????

Question

what is equation for translation of (x-2)^2 + (y+1)^2=16 by 3 units left and 5 units up?  the answer is (x-5)^2 + (y  +6)^2=16.  Why not (x+1)^2 +(y-4)^2=16.  thought move to left is positive and up is negative????

phi · Answer

See http://www.wolframalpha.com/input/?i=plot++%28x-2%29%5E2+%2B+%28y%2B1%29%5E2%3D16%2C++%28x-5%29%5E2+%2B+%28y++%2B6%29%5E2%3D16%2C%28x%2B1%29%5E2+%2B%28y-4%29%5E2%3D16 the legend in the graph shows which graph goes with which equation It looks like you are correct and the answer is bogus.