Answer:
y = 1/12 (x − 5)²
Step-by-step explanation:
We can solve this graphically without doing calculations.
The y component of the focus is y = 3. Since this is above the directrix, we know this is an upward facing parabola, so it must have a positive coefficient. That narrows the possible answers to A and C.
The x component of the focus is x = 5. Since this is above the vertex, we know the x component of the vertex is also x = 5.
So the answer is A. y = 1/12 (x−5)².
But let's say this wasn't a multiple choice question and we needed to do calculations. The equation of a parabola is:
y = 1/(4p) (x − h)² + k
where (h, k) is the vertex and p is the distance from the vertex to the focus.
The vertex is halfway between the focus and the directrix. So p is half the difference of the y components:
p = (3 − (-3)) / 2
p = 3
k, the y component of the vertex, is the average:
k = (3 + (-3)) / 2
k = 0
And h, the x component of the vertex, is the same as the focus:
h = 5
So:
y = 1/(4×3) (x − 5)² + 0
y = 1/12 (x − 5)²
P should equal 3. hope this helps.
9514 1404 393
Answer:
m∠B < m∠A < m∠C
Step-by-step explanation:
We can work with the triangle inequality to find that the side measures form a triangle when n > 5/4. For the given value of n ≥ 4, we don't need to be concerned with whether a triangle is formed or not.
For n = 4, the side lengths are ...
a = 2(4) = 8
b = (4) +3 = 7
c = 3(4) -2 = 10
The longest side is opposite the largest angle, so the ordering of angles is ...
m∠B < m∠A < m∠C
_____
The triangle inequality requires all of these inequalities be true:
- a+b > c ⇒ 3n+3 > 3n-2 . . . always true
- b+c > a ⇒ 4n+1 > 2n ⇒ n > -1/2
- c+a > b ⇒ 5n-2 > n+3 ⇒ n > 5/4
That will be the case for n > 5/4. The attached graph shows the sides and angles keep the same order for n > 3.
D
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