The general form of a parabola when using the focus and directrix is:
(x - h)² = 4p(y - k) where (h, k) is the vertex of the parabola and 'p' is distance between vertex and the focus. We use this form due to the fact we can see the parabola will open up based on the directrix being below the focus. Remember that the parabola will hug the focus and run away from the directrix. The formula would be slightly different if the parabola was opening either left or right.
Given a focus of (-2,4) and a directrix of y = 0, we can assume the vertex of the parabola is exactly half way in between the focus and the directrix. The focus and vertex with be stacked one above the other, therefore the vertex will be (-2, 2) and the value of 'p' will be 2. We can now write the equation of the parabola:
(x + 2)² = 4(2)(y - 2)
(x + 2)² = 8(y - 2) Now you can solve this equation for y if you prefer solving for 'y' in terms of 'x'
The square root of 81 is 9, this can be proven by squaring 9, which's result is 81.
Answer:
35/82 is the probability of picking a singer
Let x = price of shoes
Then price of jacket would be x - 5.81
Combining the two would give you
x + x - 5.81 = 99.15
combining like terms simplifies to 2x - 5.81 = 99.15;
now adding 5.81 to both sides of the equal sign leaves
2x = 104.96
and finally, dividing both sides by 2, gives x = $52.48; which is the cost of the shoes. Recall, the cost of the jacket is 5.81 less than the cost of the shoes.
so, COST OF THE JACKET is 52.48 - 5.81 = $46.67
