Justine and Meagan played a trivia game. Justine answered a question incorrectly and lost 7 points. Then Meagan answered correct
1 answer:
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Answer:
Step-by-step explanation:
Rearrange the equation by subtracting what is to the right of the equal sign from both sides of the equation :
Step 1 :Evaluate : (3x-9)2 = 9x^2-54x+81 = 3 • (3x^2 - 18x - 43)
Step 2: Pull out like factors :
Step 3: Trying to factor by splitting the middle term
Factoring
The first term is, its coefficient is 1 .
The middle term is, its coefficient is -6 .
The last term, "the constant", is
Step 4: Multiply the coefficient of the first term by the constant
Step-5 : Find two factors of -11 whose sum equals the coefficient of the middle term, which is -6.
Step 6:
Solve :
This equation has no solution.
A a non-zero constant never equals zero.
Find the Vertex of
Parabolas have a highest or a lowest point called the Vertex . Our parabola opens up and accordingly has a lowest point (AKA absolute minimum) . We know this even before plotting "y" because the coefficient of the first term, 1 , is positive (greater than zero).
Each parabola has a vertical line of symmetry that passes through its vertex. Because of this symmetry, the line of symmetry would, for example, pass through the midpoint of the two x -intercepts (roots or solutions) of the parabola. That is, if the parabola has indeed two real solutions.
Parabolas can model many real life situations, such as the height above ground, of an object thrown upward, after some period of time. The vertex of the parabola can provide us with information, such as the maximum height that object, thrown upwards, can reach. For this reason we want to be able to find the coordinates of the vertex.
For any parabola,A+B
+C,the x -coordinate of the vertex is given by -B/(2A) . In our case the
coordinate is 3.0000
Plugging into the parabola formula 3.0000 for x we can calculate the
-coordinate :
= 1.0 * 3.00 * 3.00 - 6.0 * 3.00 - 11.0 or
= -20.000
Root plot for
Axis of Symmetry (dashed) {x}={ 3.00}
Vertex at {x,y} = { 3.00,-20.00}
x -Intercepts (Roots) :
Root 1 at {x,y} = {-1.47, 0.00}
Root 2 at {x,y} = { 7.47, 0.00}
(Please click above graph)
Solve
by Completing The Square .
Add 11 to both side of the equation :
Now the clever bit: Take the coefficient of x , which is 6 , divide by two, giving 3 , and finally square it giving 9
Add 9 to both sides of the equation :
On the right hand side we have :
11 + 9 or, (11/1)+(9/1)
The common denominator of the two fractions is 1 Adding (11/1)+(9/1) gives 20/1
So adding to both sides we finally get :
x2-6x+9 = 20
Adding 9 has completed the left hand side into a perfect square :
Things which are equal to the same thing are also equal to one another. Since
then, according to the law of transitivity,
The Square Root Principle says that When two things are equal, their square roots are equal.
Note that the square root of
Now, applying the Square Root Principle to Eq. #3.3.1 we get:
Add 3 to both sides to obtain:
Since a square root has two values, one positive and the other negative
has two solutions:
Solving
by the Quadratic Formula .
According to the Quadratic Formula, x , the solution for Ax2+Bx+C = 0 A+B
+C
, where A, B and C are numbers, often called coefficients, is given by :
In our case, A = 1
B = -6
C = -11
Accordingly, B2 - 4AC
= 36 - (-44)
= 80
Applying the quadratic formula :
Can
be simplified ?
Yes! The prime factorization of 80 is
2•2•2•2•5
To be able to remove something from under the radical, there have to be 2 instances of it (because we are taking a square i.e. second root).
√ 80 = √ 2•2•2•2•5
= 2•2•√ 5
= ± 4 • √ 5
rounded to 4 decimal digits, is 2.2361
So now we are looking at:
x = ( 6 ± 4 • 2.236 ) / 2
Two real solutions:
Answer:
probability that you and your 3 friends will be selected.
Step-by-step explanation:
A probability is the number of desired outcomes divided by the number of total outcomes.
In this question, the order in which the volunteers are chosen is not important, which means that the combinations formula is used to solve this question.
Combinations formula:
is the number of different combinations of x objects from a set of n elements, given by the following formula.
Desired outcomes:
You and the 3 friends(4 people), from a set of 4. So
Total outcomes:
20 people from a set of 20. So
Probability:
probability that you and your 3 friends will be selected.