<p>If f: (x, y) -> (x + y, y) for every pair (x, y) in the plane, for what points (x, y) is it true that (x, y) -> (y, x)? </p>
<p>Is Sparknotes and their practice tests accurate? What about PR? Will you ever see questions exactly like the way they have it written or not? I just don't know what I should study...</p>
<p>What were the options??
(0,0) could work i think, but i doubt they would make it that easy.
(1,0) may work as well.</p>
<p>Oh, here are the options- one of which is your answer.
(A) (0, 0) only<br>
(B) (1, 1) only<br>
(C) The set of points (x, y) such that y = 0<br>
(D) The set of points (x, y) such that x = y<br>
(E) The set of points (x, y) such that 2x = y</p>
<p>I don't get how you solve this type of problem though :/</p>
<p>Just plug in all the values in the options...</p>
<p>Think about it...
just plug them in and see if they work ...
(x +y, y)
(0+0,0) = (0.0)
replace x and y --> (0,0) </p>
<p>Try that for every1 and you shud find the rite answer.</p>