Question

Which of the following statements best describes the graph of x + y = 5?

It is a line joining the points whose x and y coordinates add up to 10.

It is a line joining the points whose x and y coordinates add up to 5.

It is a line which intersects the x axis at (5, 5).

It is a line which intersects the y axis at (5, 5).

Answer 1

@e.mccormick

Answer 2

You could graph it or change it to a form you understand better.

Answer 3

That's the thing, how do I change it into a form I understand?

Answer 4

Algebra! What form do you know best? Slope-intercept (y=mx+b)?

Answer 5

Yeah, so I'd make it into y = -x + 5

Answer 6

B is the y - intercept, so the line would be crossing the y - axis, right?

Answer 7

Yes. Which means the slope is -1 and the intercept is +5, so use that to look at the answers.

Answer 8

Well, it crosses both axis, but the meaning of the y intecept is (0,y) and the x intercept is (x,0).

Answer 9

hmmmm.....so, um.....the answer is.....C.?

Answer 10

It is a line which intersects the x axis at (5, 5).

Hmm... I see a problem with that.

Answer 11

For it to intesect an axis, at least one of x or y must be 0.

Answer 12

yeah....hm... the answer is B, maybe?

Answer 13

Yes. that is the only one that makes sense. In fact, the simple definition of intercepts eliminated the last two. The first has a value that is not valid in the equation, so only B had valid information.

Answer 14

Thank you! <3

Answer 15

A graph can also help answer these:
https://www.desmos.com/calculator/j0m5kpqdtj