Solve quadratic equation by completing the square
x²+2x-15=0

Answers

Answer 1

Answer: $x^2+2x-15=0\n\nx^2+2x\cdot1+1^2-1^2=15\n\n(x+1)^2-1=15\n\n(x+1)^2=15+1\n\n(x+1)^2=16\iff x+1=4\ or\ x+1=-4\n\nx=4-1\ or\ x=-4-1\n\n\underline{\underline{x=3\ or\ x=-5}}$

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A class of 25 students took a math test. Ten students had an average of 88. The other students had an average of 76. What is the average of the whole class?A) 78.2
B) 80.8
C) 81.7
D) 82.5

Answers

Answer:

The average of the whole class is 80.8.

The correct answer is B)

Step-by-step explanation:

To solve this problem, it is very important to understand the phrase: "Ten students had an average of 88". Let's see an example.

Imagine that three students in the class took a test and their scores were: 80, 89 and 95. To calculate the average of they three we must divide the sum of the scores by the total number of scores.

$average=(80+89+95)/(3)=(264)/(3)=88$

The previous value is the average of the three students. Now, if we say that each student got 88, the average would be 88.

$average=(88+88+88)/(3)=(264)/(3)=88$

The previous expression could be simplified as:

$average=(88* 3)/(3)$

Where, the number 3 means the number of students.

With that in mind, the phrase "Ten students had an average of 88" could be written as:

$average_(10\, \, students)=(88+88+88+88+88+88+88+88+88+88)/(10)$

$average_(10\, \, students)=(88* 10)/(10)=88$

On the other hand, the phrase "The other students had an average of 76" means that from the 25 students, 15 students got 76 (25 - 10 = 15), and could be written as:

$average_(15\, \, students)=(76+76+76+76+76+76+76+76+76+76+76+76+76+76+76)/(15)$

$average_(15\, \, students)=(76* 15)/(15)=76$

Finally, to calculate the total average of the 25 students we must divide the sum of the scores of all students by the total number of scores. The sum would be: 88+88+88+88+88+88+88+88+88+88+76+76+76+76+76+76+76+76+76+76+76+76+76+76+76, which equals $88* 10+76* 15$ . The total number of scores would be: 25.

$average_(total)=(88* 10 + 76* 15)/(25)$

$average_(total)=(880 + 1140)/(25)$

$average_(total)=(2020)/(25)$

$average_(total)=80.8$

Thus, the average of the whole class is 80.8. The correct answer is B)

The answer is B. 80.8

What is the value of p?

Answers

Answer:

the answer is B

Step-by-step explanation:

everything is in the paper

The answer is b because you need to subtract 140-90= 50 P=50 140-90=P

Solve each equation (steps as to how appreciated)

Answers

Answer:

{0}

Step-by-step explanation:

|n/6| + 1 = 1

Subtract 1 from each side

|n/6| + 1-1 = 1-1

|n/6| =0

Since this is equal to zero what is inside the absolute value must equal zero

n/6 =0

n =0

Answer:

B) {0}

Step-by-step explanation:

Let's go step by step

|n/6| + 1 = 1

First step is to subtract 1 from both sides:

|n/6| = 0

Now, we can multiply both sides by 6:

n = 0

Hope this helps :)

How do you solve y=2.5x+5

Answers

if you are solving for x.
y=2.5x+5
you subtract 5 from both sides.
-5=2.5x
then divide both sides with 2.5
-5/2.5 2.5/2.5
the 2.5s will cancel each other out.
x=-2

$slope\ is\ for\ y=0\n\ny=2,5x+5\n0=2,5x+5\ \ \ | subtract\ 5\n-5=2,5x \ \ \ | divide\ by\ 2,5\nx=-2 ---> SLOPE\n\n\intercept\ is\ for\ x=0\n\ny=5----> INTERCEPT$

A system of equations can be written to represent coin and pricing problems. True or False.

Answers

The answer to this question is True. Apparently, there are a lot of mathematical problems regarding coin and pricing problems can be written with a system of equations.

I need help with 17, I have the rest just need help with 17, please.