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krissywatts
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passing through (4,2) and perpendicular to x=5/4y2. Write in slope intercept form.
 one year ago
 one year ago
krissywatts Group Title
passing through (4,2) and perpendicular to x=5/4y2. Write in slope intercept form.
 one year ago
 one year ago

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krissywatts Group TitleBest ResponseYou've already chosen the best response.0
@zepdrix
 one year ago

zepdrix Group TitleBest ResponseYou've already chosen the best response.1
is the negative 2 also in the denominator? It's a little hard to read correctly without brackets.\[\large x=\frac{5}{4y2}\]
 one year ago

zepdrix Group TitleBest ResponseYou've already chosen the best response.1
\[\large x=\frac{5}{4}y2\]Oh like this? :) That would make more sense lol
 one year ago

krissywatts Group TitleBest ResponseYou've already chosen the best response.0
no it isn't. it's like the second one you just put up.
 one year ago

zepdrix Group TitleBest ResponseYou've already chosen the best response.1
Let's first get our line into slopeintercept form, so we can accurately identify the slope. We want it in this form,\[\large y=mx+b\] \[\large x=\frac{5}{4}y2\]Start by adding 2 to each side,\[\large x+2=\frac{5}{4}y\]Multiply each side by 4/5,\[\large \frac{4}{5}(x+2)=\left(\frac{5}{4}y\right)\frac{4}{5}\]The fractions will cancel out on the right, giving us,\[\large y=\frac{4}{5}x+\frac{8}{5}\] So we've got our line in slopeintercept form, this will make it easier to work with. Understand those steps so far?
 one year ago

krissywatts Group TitleBest ResponseYou've already chosen the best response.0
oh i had put a 4/5
 one year ago

krissywatts Group TitleBest ResponseYou've already chosen the best response.0
but yes other than that i get it so far
 one year ago

zepdrix Group TitleBest ResponseYou've already chosen the best response.1
So it looks like our slope \(\large m\) is \(\large \dfrac{4}{5}\). Do you know what it means for a line to be `perpendicular`? It relates to the slope. :) Since the line we're trying to form is perpendicular to this line, it will have a slope that is a `negative reciprocal` of this slope. Do you understand what that means? c:
 one year ago

krissywatts Group TitleBest ResponseYou've already chosen the best response.0
4/5 correct? that would be the reciprocal
 one year ago

zepdrix Group TitleBest ResponseYou've already chosen the best response.1
Hmm I believe it's going to be, 5/4. Yes the negative looks good. But then we take the reciprocal (the flip) of our fraction.
 one year ago

krissywatts Group TitleBest ResponseYou've already chosen the best response.0
oh okay
 one year ago

zepdrix Group TitleBest ResponseYou've already chosen the best response.1
So we're trying to form an equation for a line perpendicular to the given line. Let's call this new line something likeeeee \(\large y_p\). So we're trying to get an equation for this line, \(\large y_p=mx+b\). We've determined that the slope is, \(\large m=\dfrac{5}{4}\). Now we need to find the \(\large b\) value, the `yintercept`. To do so, we'll plug in the coordinate pair they gave us, that this line passes through.
 one year ago

zepdrix Group TitleBest ResponseYou've already chosen the best response.1
So plug \(\large (4,2)\) into our equation \(\large y_p=\dfrac{5}{4}x+b\).
 one year ago

krissywatts Group TitleBest ResponseYou've already chosen the best response.0
i think im messing up so where
 one year ago

krissywatts Group TitleBest ResponseYou've already chosen the best response.0
for som reason im getting y=4/5x+6/5
 one year ago

krissywatts Group TitleBest ResponseYou've already chosen the best response.0
i mean 5/4x+6/5
 one year ago

zepdrix Group TitleBest ResponseYou've already chosen the best response.1
So plugging in our point gives us,\[\large 2=\frac{5}{4}(4)+b\]The 4's will cancel out,\[\large 2=\frac{5}{\cancel4}(\cancel4)+b\]Giving us,\[\large 2=5+b\]Adding 5 to each side,\[\large b=3\] Did you do something different?
 one year ago

krissywatts Group TitleBest ResponseYou've already chosen the best response.0
yeah i did
 one year ago

krissywatts Group TitleBest ResponseYou've already chosen the best response.0
i was doing it wrong
 one year ago

krissywatts Group TitleBest ResponseYou've already chosen the best response.0
so y=4/5x+8/5 is correct?
 one year ago

zepdrix Group TitleBest ResponseYou've already chosen the best response.1
This was the equation of the line we started with, \[\large y=\frac{4}{5}x+\frac{8}{5}\] They gave us a bunch of information to find a different line. And that was this line,\[\large y_p=mx+b\] We determined that the slope is \(\large m=\dfrac{5}{4}\). And that the yintercept is \(\large b=3\).
 one year ago

zepdrix Group TitleBest ResponseYou've already chosen the best response.1
The p doesn't mean anything, you don't need to put that if you don't want. It was just so we could tell it apart from our original y, which referred to a different line.
 one year ago

krissywatts Group TitleBest ResponseYou've already chosen the best response.0
so the answer is y=5/4x+3
 one year ago
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