Question

Need help in these 2 last questions!!!

Answer 1

Question 9

The point (30,15) means that x = 30 and y = 15 pair up together.

Similarly, (40,25) means we have x = 40 and y = 25 paired up.

Apply the slope formula to get

m = (y2-y1)/(x2-x1)

m = (25-15)/(40-30)

m = 10/10

m = 1

The slope is 1.

It tells us that each time y goes up by 1, x is also increasing by 1.

slope = rise/run = 1/1

rise = 1, run = 1

The rise is the change in y, the run is the change in x.

This means the plant's height (y) goes up by 1 cm each time the number of days (x) goes up by 1.

In short, the plant's height is increasing by 1 cm per day

Answer: Choice D

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Question 10

y varies directly with x, so y = kx for some constant k.

We're then told that x = -1 and y = -2 pair up together.

Let's find k based on those items

y = kx

y/x = k

k = y/x

k = -2/(-1)

k = 2

So y = kx becomes y = 2x

Then we're asked to find x when y = -4

y = 2x

y/2 = x

x = y/2

x = -4/2

x = -2

Answer: Choice D