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Mathematics 13 Online
OpenStudy (lena772):

I'm stuck..

OpenStudy (anonymous):

Question?

OpenStudy (fibonaccichick666):

with?

OpenStudy (lena772):

OpenStudy (anonymous):

me too

OpenStudy (fibonaccichick666):

So, I always recommend drawing a picture to start, It gives you a ballpark

zepdrix (zepdrix):

`So the distance to (2,1.5) is:` Did you write that line? ^ Careful, it's (2, 0.5) right?

OpenStudy (anonymous):

a point on the graph of \(y=x^2\) looks like \[(x,x^2)\] the square of the distance between that point ad \((2,\frac{1}{2})\) is \[D^2=(x-2)^2+(x^2-\frac{1}{2})^2\] you want to minimize that one

OpenStudy (anonymous):

@zepdrix good point where did the \(1.5\) come from?

OpenStudy (lena772):

k. I changed it to 0.5.

OpenStudy (fibonaccichick666):

Also, think about how you minimize a function, what does that mean?

OpenStudy (lena772):

you mean find global minimum?

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

good luck solving a cubic equation hope it was cooked up to be not too bad

OpenStudy (lena772):

it's 5 /4 when x=1

OpenStudy (fibonaccichick666):

yup to global min

OpenStudy (anonymous):

oh yeah, was this ever cooked up wait until you "simplify" the derivative amazing!

OpenStudy (anonymous):

yes it is

OpenStudy (lena772):

what am I supposed to do now?

OpenStudy (anonymous):

be happy you are done have a tequila

OpenStudy (therealmeeeee):

LOL

OpenStudy (anonymous):

don't forget what \(x\) was, it was the first coordinate of the point on the graph

OpenStudy (lena772):

so point (1, 5/4)

OpenStudy (fibonaccichick666):

Also, don't forget, when you find the x cooredinate of the global min, you need to put that into the original x^2 function

OpenStudy (anonymous):

\(\frac{5}{4}\) is the minimum distance actually it is the minimum of the square of the distance the first coordinate of the point is \(1\) and the equation is \(y=x^2\) so you can find the second coordinate without difficulty

OpenStudy (lena772):

so 1,1? what was the point of finding the minimum then?

OpenStudy (anonymous):

to find the \(x\) coordinate of the point!

OpenStudy (anonymous):

how else you going to do it? actually there is another way...

OpenStudy (fibonaccichick666):

Quite true

OpenStudy (fibonaccichick666):

minimizing the distance formula by finding the derivative makes your life wonderfully easy, you just have to remember to input the x value back into the original not use the value of the derivative :)

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