Answer:
A. y = -5x
Explanation:
These are simple, especially when they give you four choices:
Simply plug any of the non-zero points into the equation and see if it works.
Let's start with the first equation, y = -5x, and the first point (-2,10). Substitute those numbers in for x and y and see if the equation is true:
10 = -5(-2) = 10
10 = 10, that's true, so we're done.
But just to practice some more, let's try (1,-5) in C,. y = 5x:
-5 = 5(1) = 5 <-- NOT true, negative 5 doesn't equal five.
They tried to trick us on that one: notice how the equation in c looks a lot like the one in a, but a has a negative sign. That's what made that one work for the given points.
But there's another way to think about these, and that's by noticing the relationship between x and y in the given points. Leaving the signs off for a minute, what do (1,5) and (2,10) have in common? y is 5 times bigger in both. See the word 'times'? That immediately told me that x was going to have to have a multiplier of 5. Then you just have to figure out the signs that make it work.
Notice B and D: they added/subtracted 5, trying to trick us.
Yes, there's the idea of a '5' in those, but adding/subtracting doesn't work.
And you can't use the point (0,0) to check because the zeroes tend to make both sides zero, and cancel the signs out. Notice how (0,0) works in A and C, but we know C isn't correct. So don't use the (0,0) point on these kinds of questions.