<span> first, write the equation of the parabola in the required form: </span>
<span>(y - k) = a·(x - h)² </span>
<span>Here, (h, k) is given as (-1, -16). </span>
<span>So you have: </span>
<span>(y + 16) = a · (x + 1)² </span>
<span>Unfortunately, a is not given. However, you do know one additional point on the parabola: (0, -15): </span>
<span>-15 + 16 = a· (0 + 1)² </span>
<span>.·. a = 1 </span>
<span>.·. the equation of the parabola in vertex form is </span>
<span>y + 16 = (x + 1)² </span>
<span>The x-intercepts are the values of x that make y = 0. So, let y = 0: </span>
<span>0 + 16 = (x + 1)² </span>
<span>16 = (x + 1)² </span>
<span>We are trying to solve for x, so take the square root of both sides - but be CAREFUL! </span>
<span>± 4 = x + 1 ...... remember both the positive and negative roots of 16...... </span>
<span>Solving for x: </span>
<span>x = -1 + 4, x = -1 - 4 </span>
<span>x = 3, x = -5. </span>
<span>Or, if you prefer, (3, 0), (-5, 0). </span>
Answer: x = 0
Step-by-step explanation:
1 - 3x = 3x + 1
then add 3x on both sides
1 = 6x + 1
then subtract 1 on both sides
0 = 6x
then divide by 6 on both sides
0 = x
so x = 0
The '68-95-99.7' rule says
-About 68% of values fall within one standard deviation of the mean.
-About 95% of the values fall within two standard deviations from the mean.
-Almost all of the values — about 99.7% — fall within three standard deviations from the mean.
Here 
Therefore, the probability

The required probability

The answer is 0. While the answer for n is approximately 2.384503, there are no EXTRANEOUS solutions. Again, the answer is a.) 0
Answer:
The answer to your question is He must get 80%
Step-by-step explanation:
Data
Scores 55%, 78%, 84%, 93% and X
Average 80%
Process
1.- Write a equation to solve this problem
- There are five scores
Score 1 = S1 = 55
Score 2 = S2 = 78
Score 3 = S3 = 84
Score 4 = S4 = 93
Score 5 = S5 = X
Equation
Average = (S1 + S2 + S3 + S4 + S5) / 5
- Solve for S5
5 Average = S1 + S2 + S3 + S4 + S5
S5 = 5 Average - S1 - S2 - S3 - S4
- Substitution
S5 = 5(80) - 55 - 78 - 84 - 93
- Simplification
S5 = 400 - 310
- Result
S5 = 90