A proportion looks like this:
It means that the quantity a,b,c and d are in the same proportion: the ratio between a and b is the same ratio between c and d.
They are particularly useful in situation when you have an example given, and you want to extrapolate the relationship for another couple.
For example, you can think of the following problem: "Five apples cost 2 dollars. How much will 8 apples cost?"
You can build the proportion
And then solve it for x:
Write the correct equation. Direct variation problems are solved using the equation y = kx. When dealing with word problems, you should consider using variables other than x and y, you should use variables that are relevant to the problem being solved. Also read the problem carefully to determine if there are any other changes in the direct variation equation, such as squares, cubes, or square roots.
(-2,6) (5,-8)
slope = (y2 - y1) / (x2 - x1)
slope = (-8 - 6) / (5 - (-2) = -14/7 = -2 <==
midpoint = (x1 + x2)/2 , (y1 + y2)/2
m = (-2 + 5)/2 , (6 - 8)/2
m = (3/2, -1) <===
distance = sqrt ((x2 - x1)^2 + (y2 - y1)^2)
d = sqrt ((5 - (-2)^2 + (-8 - 6)^2)
d = sqrt ((5 + 2)^2 + (-14^2))
d = sqrt (7^2 + 14^2)
d = sqrt (49 + 196)
d = sqrt 245
d = 15.65 <==
2304 cubic inches. You multiply the length, width, and base
