Answer:
Step-by-step explanation:
Any point on a given parabola is equidistant from focus and directrix.
Given:
Focus of the parabola is at 
.
Directrix of the parabola is 
.
Let 
be any point on the parabola. Then, from the definition of a parabola,
Distance of from focus = Distance of from directrix.
Therefore,
Squaring both sides, we get
![(x-2)^{2}+(y-8)^{2}=(y-10)^{2}\\(x-2)^{2}=(y-10)^{2}-(y-8)^{2}\\(x-2)^{2}=(y-10+y-8)(y-10-(y-8))...............[\because a^{2}-b^{2}=(a+b)(a-b)]\\(x-2)^{2}=(2y-18)(y-10-y+8)\\(x-2)^{2}=2(y-9)(-2)\\(x-2)^{2}=-4(y-9)\\y-9=-\frac{1}{4}(x-2)^{2}\\y=-\frac{1}{4}(x-2)^{2}+9](https://tex.z-dn.net/?f=%28x-2%29%5E%7B2%7D%2B%28y-8%29%5E%7B2%7D%3D%28y-10%29%5E%7B2%7D%5C%5C%28x-2%29%5E%7B2%7D%3D%28y-10%29%5E%7B2%7D-%28y-8%29%5E%7B2%7D%5C%5C%28x-2%29%5E%7B2%7D%3D%28y-10%2By-8%29%28y-10-%28y-8%29%29...............%5B%5Cbecause%20a%5E%7B2%7D-b%5E%7B2%7D%3D%28a%2Bb%29%28a-b%29%5D%5C%5C%28x-2%29%5E%7B2%7D%3D%282y-18%29%28y-10-y%2B8%29%5C%5C%28x-2%29%5E%7B2%7D%3D2%28y-9%29%28-2%29%5C%5C%28x-2%29%5E%7B2%7D%3D-4%28y-9%29%5C%5Cy-9%3D-%5Cfrac%7B1%7D%7B4%7D%28x-2%29%5E%7B2%7D%5C%5Cy%3D-%5Cfrac%7B1%7D%7B4%7D%28x-2%29%5E%7B2%7D%2B9)
Hence, the equation of the parabola is .
Answer:
b
Step-by-step explanation:
Answer:
a) 7 weeks b) George's
Step-by-step explanation:
Sally's score can be modeled by 10x+850.
George's score can be modeled by 50x+570.
We can set them equal to each other to see when they intersect.
10x+850=50x+570
40x=280
x=7
If George overtakes her in the 7th week, of course he'll have the higher score in 12 weeks.
Answer:
Therefore, the pairs of twin-prime numbers are (101,103) , (107,109) , (137,139) , (149,151) , (179,181) , (191,193) , (197,199) . So, the correct answer is “ (101,103) , (107,109) , (137,139) , (149,151) , (179,181) , (191,193) , (197,199) ."
-Answer:Option B: Increase the amount of money they save each month by $80 from what they've been saving.
Step-by-step explanation: Only option B will allow them to meet their goal.
