What is 70 divided by 7 1/2
2 answers:
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Answer:
Step-by-step explanation:
Look at the component form of each vector.
Note that vector c is <4,4> and vector d is <-2,-2>
If one imagined the line that contained each vector, the line for both would have a slope of 1, because
Since they have the same slope they are parallel, but since they are in opposite directions, we often call them "anti-parallel" (simply meaning parallel, but in opposite directions).
If two vectors are parallel, one vector can be multiplied by a scalar to result in the other vector. This means that there is some number "k", such that , or equivalently,
and
.
If and
, we just need to substitute known values and solve for k:
Double checking that k works for the y-coordinates as well:
?
So,
So hmmmmm, notice... the boat went up in 3hrs, came back to the starting point in 2hrs, it went up 108km, it came back, well, from 108km to distance 0, so the distance on the way back is just the same 108km
now... let's say the stream has a speed rate of "r", and the boat has a still water speed rate of "b"
bear in mind that, when the boat is going UP, is not really going "b" fast, because the stream's "r" rate is going against it, and thus subtracting "r" from "b", so is really going " b - r " fast
when the boat is going down, is not going "b" fast either, because, again the stream's rate "r" is adding to it, because is going with the current, so is really going " b + r " fast
now, recall your d =rt, distance = rate * time
solve for "r"
what's b? well, 36+ r = b
now... let's say the stream has a speed rate of "r", and the boat has a still water speed rate of "b"
bear in mind that, when the boat is going UP, is not really going "b" fast, because the stream's "r" rate is going against it, and thus subtracting "r" from "b", so is really going " b - r " fast
when the boat is going down, is not going "b" fast either, because, again the stream's rate "r" is adding to it, because is going with the current, so is really going " b + r " fast
now, recall your d =rt, distance = rate * time
solve for "r"
what's b? well, 36+ r = b