Answer:
a : c = 7 : 10
Step-by-step explanation:
The two ratios (a : b and b : c) both have b in common, so to work out what a : c is, we can use b to 'bridge' the two ratios together.
However, in a : b, b is 4. But in b : c, b is 2. We need to make sure b is the same in both ratios before we can combine the ratios together. The easiest way to do this is to multiply b : c by 2 to get b : c = 4 : 10. Now b is 4 in both ratios.
So now, we can combine the two ratios together to get a : b : c = 7 : 4 : 10. Since we only want a : c though, we can just drop the b and get a : c = 7 : 10. No simplifying is necessary since the ratio is already in its simplest form.
Hope that helps! :)
Yes this is the right answer
The general form for a line through two points (a,b) and (c,d) is
(c-a)(y-b)=(d-b)(x-a)
This is better than the slope forms because it works in the no slope case, as does the standard form.
If you haven't seen it before, it works because when (x,y)=(a,b) we get (c-a)(b-b)=(d-b)(a-a), both sides zero, and when (x,y)=(c,d) we get (c-a)(d-b)=(d-b)(c-a), clearly equal sides.
Here we have
(0 - -5)(y - 0) = (-9 - 0)(x - - 5)
5y = -9(x+5)
5y = -9x - 45
9x + 5y = -45
Ironically there are two standards for standard form; one with the constant alone on the right and one with the whole thing equal to zero. I like the constant alone.
Answer: 9x + 5y = -45
Check:
We check each point is on the line
(-5,0)
9(-5) + 5(0) = -45, good
(0, -9)
9(0) + 5(-9) = -45, good again
To find the average rate of change, evaluate the function at the given points.
Evaluate the difference of the function at the given points.
Divide the difference of the function at the given points with the difference of the given points.
