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 is the slope of a line passing through the points (3, 5) and (1, 2)?
+
What is the equation of a line that passes through the points (2,4) and (5,7)?
+
Question: A car travels at an average speed of 60 mph for 2.5 hours. What distance does it cover?
+
New questions in Mathematics
How to find the value of x and y which satisfy both equations x-2y=24 and 8x-y=117
-6n+5=-13
Since one of the three integers whose product is (-60) is (+4), write the values that two integers can take.
2x-y=5 x-y=4
Kayla has $8,836.00 in her savings account. The bank gives Kayla 5%of the amount of money in account as a customer bonus. What amount of money does the bank give Kayla? Justify your answer on a 6th grade level.
Identify a pattern in the list of numbers.Then use this pattern to find the next number. 37,31,25,19,13
Pedro had 80% of the amount needed to buy a game. Of this amount, you spent 15% on a watch and therefore, you will need to add another R$640.00 to purchase this game. Is the value of the game?
In a grocery store, when you take out 3 peppers and 4 carrots, there are 26 peppers and 46 carrots left. How many peppers and carrots were there initially?
Determine the general equation of the straight line that passes through the point P (2;-3) and is parallel to the straight line with the equation 5x – 2y 1 = 0:
A person decides to invest money in fixed income securities to redeem it at the end of 3 years. In this way, you make monthly deposits of R$300.00 in the 1st year, R$400.00 in the 2nd year and R$500.00 in the 3rd year. Calculate the amount, knowing that compound interest is 0.6% per month for the entire period. The answer is 15,828.60
TEST 123123+1236ttttt
Buffalo Company makes and sells shampoo. Each unit requires $1.40 labor costs, material costs per unit are $0.90 and other variable costs are $0.30. It sells shampoo for $4.45 to retailers. Fixed costs are $15,000. It sold 25,000 units in the current month. What is the Break-Even point in units? What is the Break-Even point in dollars? What is the contribution margin of Buffalo Company?
Express the trigonometric form of the complex z = -1 + i.
In measuring the internal radius of a circular sewer the measurement is 2% too large. If this measurement is then used to calculate the circular cross-sectional area of the pipe: Determine, by using the binomial theory, the percentage error that will occur compared to the true area.
5x+13+7x-10=99
A building lot is in the shape of a triangle with a base of 133 feet and a height of 76 feet. What is it's area in square feet?
simplify w+[6+(-5)]
16-(x²+x+2)²
Define excel and why we use it?
A gas is leaking at 3.5ft3/min in a room of 2.9m by 6.9ft by 15.7m. How long would it take (in seconds) for 22% of the room to reach the LFL, if the gas has a LFL of 2.51%?