Question

If the line D: x = 1 is the directrix of the parabola p: y raised to the power of 2 - kx + 8 = 0, then one of the values of k can be:

198

likes
988 views

Answer to a math question If the line D: x = 1 is the directrix of the parabola p: y raised to the power of 2 - kx + 8 = 0, then one of the values of k can be:

Expert avatar
Jayne
4.4
106 Answers
### Step-by-Step Solution:

### Step 1: Rewrite the parabola equation in standard form

y^2 = kx - 8

### Step 2: Identify vertex form and properties of the parabola

p = \frac{k}{4}

### Step 3: Determine the vertex

\left(\frac{8}{k}, 0\right)

### Step 4: Location of the directrix

The directrix is at:

x = \frac{8}{k} - \frac{k}{4}

Given the directrix is \( x = 1 \):

\frac{8}{k} - \frac{k}{4} = 1

Simplify and solve the equation:

8 - \frac{k^2}{4} = k

\frac{k^2}{4} + k - 8 = 0

k^2 + 4k - 32 = 0

### Step 5: Solve the quadratic equation

Use the quadratic formula \( k = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \):

k = \frac{-4 \pm \sqrt{144}}{2}

k = \frac{-4 \pm 12}{2}

Thus, the solutions are:

k = \frac{-4 + 12}{2} = 4

k = \frac{-4 - 12}{2} = -8

Verify which value matches the directrix condition:

- For \( k = 4 \):

\frac{8}{4} - \frac{4}{4} = 2 - 1 = 1

This matches.

- For \( k = -8 \):

\frac{8}{-8} - \frac{-8}{4} = -1 + 2 = 1

This also matches.

Therefore, \( k = 4 \) satisfies the condition.

\boxed{k = 4}

Frequently asked questions (FAQs)
What are the characteristics of the cotangent function f(x) = cot x? How does it behave as x approaches 0? As x approaches positive infinity and negative infinity? As x approaches vertical asymptotes? Does it have any x-intercepts or y-intercepts?
+
Math question: If a shirt costs $30 and is on sale for 20% off, how much will the shirt cost after the discount? (
+
Math question: Convert the number 0.0000642 into scientific notation.
+
New questions in Mathematics
A car tire can rotate at a frequency of 3000 revolutions per minute. Given that a typical tire radius is 0.5 m, what is the centripetal acceleration of the tire?
(x^2+3x)/(x^2-9)=
What is the coefficient of elasticity of the material that must be placed on the heel of the 10 cm high clog, with a base area of 2 cm² so that it deforms only 2 cm when the force on it will be a maximum of 600 N.
what is 9% of 307
solve the following trigo equation for 0°<= x <= 360°. sec x =-2
x/20*100
4x567
All the liquid contained in a barrel is distributed into 96 equal glasses up to its maximum capacity. We want to pour the same amount of liquid from another barrel identical to the previous one into glasses identical to those used, but only up to 3/4 of its capacity. How many more glasses will be needed for this?
(5u + 6)-(3u+2)=
Identify a pattern in the list of numbers.Then use this pattern to find the next number. 37,31,25,19,13
is the x element (180,270), if tanx-3cotx=2, sinx ?
2x2 and how much?
-3(-4x+5)=-6(7x-8)+9-10x
A study reports the following final notation: F (3, 32) = 9.50, p < .05. How many total participants were involved in this study? Group of answer choices 34 32 36
I want you to solve this problem as a grade sixth pupil in primary school: 8 Pigs ate 6 bags of fee in 20 days. How long will it take 10 pigs to eat 15 bags of feed eating at the same rate?
The price per night of a suite at the Baglioni Hotel in Venice is 1896 euros, VAT included. The VAT in Italy is 25%. The hotel gets a return of 10% out of the price VAT included. b) What is the profit value made by the hotel for one
The probability of growing a seedling from a seed is 0.62. How many seeds do I need to plant so that the probability of growing at least one seedling is greater than or equal to 0.87?
Find the vertex F(x)=x^2-10x
Find I (Intrest) using simple interest formula of 17700 @ 15% for 4 years
t+72/t=-17