Basically, the parabola has to have all points that are equidistant from the focus and the directrix, the directrix being a horizontal line, and the focus being a point given. To derive an equation from this you need to use the distance formula which I'm guessing you already know because you're already in precalc.
The gist of it is that we have a random point on the parabola (x,y), and the point (x,y) will be equidistant from both the focus and the directrix. If we use the distance formula, you get something like this:

The square root of y-(-1/2) coming from the directrix, and the righthand side of the equal sign being derived from the focus.
All you need to do is simplify now!
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Hope I helped!
Answer:
1.625
Step-by-step explanation:
Add 13 to both sides
8n = 26 - 8n
Add 8n to both sides
16n = 26
Divide both sides by 16
Your answer is 1.625
Hope I helped :)
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Answer:
yes she will have enough, they will have 17 dollars left
Step-by-step explanation:
84 times 5 is 420 so she will have enough
Answer:
59 meters
Step-by-step explanation:
A=L*W
165=L*22
L=165/22=7.5
7.5=L
P=L+L+W+W
7.5+7.5+22+22=59
Answer:
A
Step-by-step explanation:
We know that identity:
cos^2x+sin^2x=1.
From that we have:
cos^2x=1-sin^2x.
So it is:
cos^2x-sin^x=(1-sin^2x)-sin^2x=1-2sin^2x.
And this is A).
B) is not treu because cos^2 is not sin^2x+1
C) is not true because cos^2x-sin^x=1 is false.
D) is not treu because cos^2x is not sin^2x-1