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Dahasolnce [82]
2 years ago
14

hey, can someone please double check these questions for me / or help me solve them if they are incorrect? thank you U-U ​

Mathematics
1 answer:
zzz [600]2 years ago
8 0

Question 11

The directrix is a horizontal line, which means the parabola opens either upward or downward. In this case, it opens downward. This is because all answer choices have a negative leading coefficient. Also, it's because the focus is below the directrix.

For vertically opening parabolas, we use this form

4p(y-k) = (x-h)^2

where (h,k) is the vertex and p is the focal distance, aka the distance from the vertex the focus. To find (h,k), we start at the focus (0,-4) and move directly up until we reach the directrix y = 4. We'll arrive at (0,4). The midpoint of (0,-4) and (0,4) is (0,0) which is the vertex's location. So (h,k) = (0,0).

Note that in moving from (0,-4) to (0,4) is a span of 4 units. So this is the value of p.

Plug h = 0, k = 0, p = 4 into the equation mentioned and solve for y

4p(y-k) = (x-h)^2

4*4(y-0) = (x-0)^2

16y = x^2

y = (1/16)x^2

The only adjustment we need to make is to change the 1/16 to -1/16 so that the parabola opens downward.

<h3>Answer:  Choice D.  y = -(1/16)x^2</h3>

===============================================

Question 3

The given equation is in the form y = ax^2+bx+c

In this case,

  • a = 2
  • b = 4
  • c = 3

Let's compute the x coordinate of the vertex h

h = -b/(2a)

h = -4/(2*2)

h = -1

This h value is plugged into the original function to find k

f(x) = 2x^2+4x+3

f(-1) = 2(-1)^2+4(-1)+3

f(-1) = 1

We find that h = -1 and k = 1 pair up together. In short, (h,k) = (-1,1) is the vertex.

<h3>Answer: Choice B.  (-1,1)</h3>
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Answer:

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Step-by-step explanation:

to find the equation of a line with 2 points, we use the slope formula which is:

\frac{y_2-y_1}{x_2-x_1}

we will use (6,4) as x_1[tex] and [tex]y_1 and we will use (-3,-8) as x_2[tex] and [tex]y_2. we plug this into the slope formula:

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but we can simplify this further by dividing the fraction by -3

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the simplified version of the slope is \frac{4}{3}

we can write this in slope-intercept form which is y =mx + b, with b being the y intercept and m being the slope

y = 4/3x + b <--- we need to solve for <em>b</em> in order to find the y intercept, so substitute x & y for a point on the line, we can use any point we are given, but for this example i will use (6,4)

4 = 4/3(6) + b < multiply 4/3 x 6

4 = 8 + b < subtract 8 from both sides

-4 = b

our y intercept would be (0,-4)

the equation looks like the following:

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Answer:

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Answer:

e = 56

Step-by-step explanation:

Use cross multiplication.

28 * 14 = 7e

Simplify

392 = 7e

Divide each side by 7

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