Which relation is a function? {(4, 2), (3, 3), (2, 4), (3, 2)}

{(1, 2), (2, 3), (3, 2), (2, 1)}

{(1, −1), (−2, 2), (−1, 2), (1, −2)}

{(1, 4), (2, 3), (3, 2), (4, 1)}

Choice D)

{(1, 4), (2, 3), (3, 2), (4, 1)}

Explanation:

Let's go through the answer choices one at a time to see what is a function and what isn't.

In short, choices A,B,C are not functions because they have a repeated x coordinate; in contrast, choice D doesn't have any repeated x values so it is a function.

Side note: The y values are allowed to repeat themselves, but the function won't be one-to-one.

answer: i believe its b. if you sound out the sentences that sounds wrong.

{x = -1/2 ,   y = -1

step-by-step explanation:

solve the following system:

{2 x + y = -2

{10 x - 3 y = -2

in the first equation, look to solve for y:

{2 x + y = -2

{10 x - 3 y = -2

subtract 2 x from both sides:

{y = -2 x - 2

{10 x - 3 y = -2

substitute y = -2 x - 2 into the second equation:

{y = -2 x - 2

{10 x - 3 (-2 x - 2) = -2

10 x - 3 (-2 x - 2) = (6 x + 6) + 10 x = 16 x + 6:

{y = -2 x - 2

{16 x + 6 = -2

in the second equation, look to solve for x:

{y = -2 x - 2

{16 x + 6 = -2

subtract 6 from both sides:

{y = -2 x - 2

{16 x = -8

divide both sides by 16:

{y = -2 x - 2

{x = -1/2

substitute x = -1/2 into the first equation:

{y = -1

{x = -1/2

collect results in alphabetical order:

answer:   {x = -1/2 ,   y = -1