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3 years ago

6

Derive the equation of the parabola with a focus at (2, 4) and a directrix of y = 8.

1 answer:

4vir4ik [10]3 years ago

6 0

Directrix y = 8
It is a horizontal line so the parabola is vertical.
<span>The focus (2, 4) lies below the directrix,
Therefore parabola opens downwards. </span>
<span>vertex will be halfway between focus and directrix, at (2, 6) </span>
<span>focal length =p
= distance between focus and vertex
= 2 </span>
<span>y = (-1/(4p))(x - 2)² + 6 </span>
<span>y = (-1/8)(x - 2)² + 6
hope this helps</span>

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Which equations represent the line that is perpendicular to the line 5x − 2y = −6 and passes through the point (5, −4)? Select t

Pepsi [2]

Answer:

Step-by-step explanation:

Two lines are perpendicular if the first line has a slope of $m$ and the second line has a slope of $\frac{1}{-m}$ .

With this information, we first need to figure out what the slope of the line is that we're given, and then we can determine what the slope of the line we're trying to find is:

$5x - 2y = -6$

$-2y = -5x - 6$

$y = \frac{5}{2}x + 3$

We now know that $m = \frac{5}{2}$ for the first line, which means that the slope of the second line is $m = \frac{-2}{5}$ . With this, we have the following equation for our new line:

$y = \frac{-2}{5}x + C$

where $C$ is the Y-intercept that we now need to determine with the coordinates given in the problem statement, $(5, -4)$ :

$y = \frac{-2}{5}x + C$

$(-4) = \frac{-2}{5}(5) + C$

$-4 = -2 + C$

$C = -2$

Finally, we can create our line:

$y = \frac{-2}{5}x - 2$

$5y = -2x - 10$

$2x + 5y = -10$

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Solve the system by using the technique of ‘elimination’: -2x+5y=-42,7x+2y=30

Gekata [30.6K]

Solve the following system using elimination:

{5 y - 2 x = -42 | (equation 1)

7 x + 2 y = 30 | (equation 2)

Swap equation 1 with equation 2:

{7 x + 2 y = 30 | (equation 1)

-(2 x) + 5 y = -42 | (equation 2)

Add 2/7 × (equation 1) to equation 2:

{7 x + 2 y = 30 | (equation 1)

0 x+(39 y)/7 = (-234)/7 | (equation 2)

Multiply equation 2 by 7/39:

{7 x + 2 y = 30 | (equation 1)

0 x+y = -6 | (equation 2)

Subtract 2 × (equation 2) from equation 1:

{7 x+0 y = 42 | (equation 1)

0 x+y = -6 | (equation 2)

Divide equation 1 by 7:

{x+0 y = 6 | (equation 1)

0 x+y = -6 | (equation 2)

Collect results:

Answer: {x = 6, y = -6

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What is the Slope of the line

vampirchik [111]

Answer:

$m=\frac{-3}{4}$

Step-by-step explanation:

Slope Formula: $m=\frac{y_2-y_1}{x_2-x_1}$

Simply plug in 2 coordinates into the slope formula to find slope <em>m</em>:

$m=\frac{-4-(-1)}{5-1}$

$m=\frac{-4+1}{4}$

$m=\frac{-3}{4}$

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