Here's an example...
So, in our last example...
In the point ( -2, -1 ), x1 = -2 and y1 = -1 ... and, in the point ( 4, 3 ), x2 = 3 and y2 = 3
m = ( y2 - y1 ) / ( x2 - x1 ) = ( 3 - ( -1 ) ) / ( 4 - ( -2 ) ) = 4 / 6 = 2 / 3
But, notice something cool...
The order of the points doesn't matter! Let's switch them and see what we get:
In the point ( 4, 3 ), x1 = 4 and y1 = 3 ... and, in the point ( -2, -1 ), x2 = -2 and y2 = -1
m = ( y2 - y1 ) / ( x2 - x1 ) = ( -1 - 3 ) / ( -2 - 4 ) = -4 / -6 = 2 / 3 ... Same thing!
Let's try our new formula with the second example in the last lesson:
It was a line passing through
( -1, 4 ) and ( 2, -2 )
m = ( y2 - y1 ) / ( x2 - x1 ) = ( -2 - 4 ) / ( 2 - ( -1 ) ) = -6 / 3 = -2
Step-by-step explanation:
Start at 5 on the y axis then for the next point go up 3 and 8 to the right
The question can't be answered with the information given.
First of all, we don't know how fast the rain is falling ... how many inches
per hour.
But even of we knew that, that would only tell us how much water would
pile up in our yard or on our street. You're talking about a river, and
that's a whole different ball game.
The rain that falls right here is going to flow down the river to somewhere
else. But the rain that falls up-river from us is going to flow down to where
we are, and the river is going to rise. The amount it rises depends on . . .
-- how fast the rain is falling,
-- how much area it's falling on,
-- how much forest there is in that area and how many houses and
parking lots where the ground can't soak up the water and hold it,
-- and also on how wide the river is and how fast the water can flow through it.
