Answer: 27.52
Step-by-step explanation:
To answer the problem above, use the concept of ratio and proportion. The ratio between 1 cm to 21 km should be the same as the ratio of 3.1 cm to the actual distance. Let x be the unknown actual distance and mathematically express the situation,
(1 cm/ 21 km) = (3.1 cm / x km)
This equation gives a value for x which is 65.1 km. Therefore, the answer is letter C.
Answer:

Step-by-step explanation:
You know that
and have to find

Use the main properties of exponents:
1. 
2. 
Note that

then

Now

Since
then 
<span>1) 2p = -2.
<span> 4p [ y - k ] = [ x - h) ]² --- > - 4 [ y + 5 ] = [ x + 5 ]²
2) </span></span><span>4p * (y - k) = (x - h)^2 </span>
<span>(h , k) is the vertex </span>
<span>The vertex is halfway between the focus and the directrix (when they're at their closest) </span>
<span>p is that distance </span>
<span>2 - 1 = 1 </span>
<span>4p = 1 </span>
<span>p = 1/4 </span>
<span>(1/4) * (y - k) = (x - h)^2 </span>
<span>y - k = 4 * (x - h)^2 </span>
<span>The vertex is at (6 , 3/2), since that's midway between (6 , 1) and (6 , 2) </span>
<span>y - 3/2 = 4 * (x - 6)^2 </span>
<span>y = (3/2) + 4 * (x - 6)^2
</span><span>
4) </span><span>f(x) = (-1/16)*(x²)
</span><span>
5) </span><span>f(x) = −1/4 x2 − x + 5</span><span>
</span>