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3 years ago

Consider the parabola represented by the equation -2y^2=4x

1 answer:

5 0

Part 1: The general form for this matches y^2 = -4cx, which implies that this opens to the left. (Imagine assigning any value of y, whether positive or negative, which would result in a positive left-hand value. Then to match this sign, the value of x must be negative so that the right-hand side becomes positive as well.)

Part 2: The distance from the vertex to the directrix is given by c. This equation has its vertex at the origin (0, 0). If it opens to the left, the directrix is a vertical line to the right of the origin. This equation is y^2 = -4(1/2)x, so c = 1/2, and the directrix has the equation x = 1/2.

Part 3: The focus is inside the parabola, but it is the same distance from the vertex as the directrix. This distance is 1/2 units, and it will be to the left of the vertex. So the focus is at (-1/2, 0).

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Gennadij [26K]

Answer:

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Step-by-step explanation:

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2 years ago

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Salena, Justin, and Brandon were riding their bikes to the library after school. The library is 12 1/2 miles from school. Salena

faust18 [17]

Answer:

Salena's got to the library first

Step-by-step explanation:

12½ miles = 25/2 miles

2½ miles = 5/2 miles

5¾ miles = 23/4 miles

114 miles = 114 miles

Salena's time of arrival =

if 5/2 miles : 5 minutes

then 25/2 miles : ?

25/2 ÷ 5/2. × 5

25/2 × 2/5 × 5

25 minutes

Justin 's time of arrival=

if 23/4 miles : 12 minutes

25/2 miles : ?

25/2 ÷ 23/4 ×12

25/2 × 4/23 ×12

26 minutes approximately

Brandon 's time of arrival=

if 114 miles : 258 minutes

25/2 miles : ?

25/2 ÷114 ×258

25/2 × 1/114×258

25 × 1/57 × 258

113 minutes approximately

3 0

3 years ago

Find the measure of angle E.

9966 [12]

Add all of the interior angles to 1260. Then you simplify for x. After that you plug in what you found for X in the E expression.

4 0

3 years ago

Suppose Upper F Superscript prime Baseline left-parenthesis x right-parenthesis equals 3 x Superscript 2 Baseline plus 7 and Upp

Sedaia [141]

It looks like you're given

F'(x) = 3x² + 7

and

F (0) = 5

and you're asked to find F(b) for the values of b in the list {0, 0.1, 0.2, 0.5, 2.0}.

The first is done for you, F (0) = 5.

For the remaining b, you can solve for F(x) exactly by using the fundamental theorem of calculus:

$F(x)=F(0)+\displaystyle\int_0^x F'(t)\,\mathrm dt$

$F(x)=5+\displaystyle\int_0^x(3t^2+7)\,\mathrm dt$

$F(x)=5+(t^3+7t)\bigg|_0^x$

$F(x)=5+x^3+7x$

Then F (0.1) = 5.701, F (0.2) = 6.408, F (0.5) = 8.625, and F (2.0) = 27.

On the other hand, if you're expected to approximate F at the given b, you can use the linear approximation to F(x) around x = 0, which is

F(x) ≈ L(x) = F (0) + F' (0) (x - 0) = 5 + 7x

Then F (0) = 5, F (0.1) ≈ 5.7, F (0.2) ≈ 6.4, F (0.5) ≈ 8.5, and F (2.0) ≈ 19. Notice how the error gets larger the further away b gets from 0.

A better numerical method would be Euler's method. Given F'(x), we iteratively use the linear approximation at successive points to get closer approximations to the actual values of F(x).

Let y(x) = F(x). Starting with x₀ = 0 and y₀ = F(x₀) = 5, we have

x₁ = x₀ + 0.1 = 0.1

y₁ = y₀ + F'(x₀) (x₁ - x₀) = 5 + 7 (0.1 - 0) → F (0.1) ≈ 5.7

x₂ = x₁ + 0.1 = 0.2

y₂ = y₁ + F'(x₁) (x₂ - x₁) = 5.7 + 7.03 (0.2 - 0.1) → F (0.2) ≈ 6.403

x₃ = x₂ + 0.3 = 0.5

y₃ = y₂ + F'(x₂) (x₃ - x₂) = 6.403 + 7.12 (0.5 - 0.2) → F (0.5) ≈ 8.539

x₄ = x₃ + 1.5 = 2.0

y₄ = y₃ + F'(x₃) (x₄ - x₃) = 8.539 + 7.75 (2.0 - 0.5) → F (2.0) ≈ 20.164

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2 years ago

Tomas got a score of 75% correct on an exam. There were 24 questions on the exam. What number of questions did Tomas get correct

laila [671]

The answer to this problem will be D

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2 years ago

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