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Ivan
4 years ago
12

Help answering these math questions

Mathematics
2 answers:
Leto [7]4 years ago
5 0
I’m pretty sure the first one is c
Gwar [14]4 years ago
5 0

Answer:

Step-by-step explanation:

1. y = x^{2}  - 2x- 15 = x^{2}  - 5x +3x -15 = x(x-5) + 3(x-5) = (x-5)(x+3)

2.

4x^{2}  - 8x - 12 = 0\\x^{2} - 2x - 3 = 0\\x^{2} - 3x + x - 3 = 0\\ x(x-3) + 1 (x-3) = 0\\(x-3)(x+1) = 0

x= 3 and x = -1

3. x^{2}  - 36 = 0

  (x-6) (x+6) = 0

x = 6 and -6

You might be interested in
Use the exponential function y=500(.9)^x to find the value of the video game console after 4 years.
zysi [14]

Answer:

328.05 dollars

7 years

Step-by-step explanation:

1.

y=500(.9)^4 =328.05

What is being asked in the problem and what does that mean?

We are asked to the price of the video game after 4 years.

What do I know and what does it mean? What plan am I going to try?

We know the <u>initial price is $500</u>, the <u>value depreciates 10% each year </u>because we have .9 or 90% of the price going into the next year.

- value of the video game after first year 90% of 500 so is 450

- value of the video game after second year 90% of 450 so is 405

-value of the video game after third year 90% of 405 so is 364.5

-value of the video game after <u>fourth year</u> 90% of 364.5 so is 328.05

The plan is to substitute x with 4 and calculate y, y=500(.9)^4

What is your answer and what does it mean?

The answer is $328.05, and it means that the video game that was initially worth $500 it lost its' value by 10 % each of the four years.

2.

         y= 500(.9)^x

----------------------------------------------------------------------------

x =8, y= 500(0.9)^8 = 215.234 ≈215.23, this is less than $250

x = 7, y= 500(0.9)^7 = 239.148 ≈239.15, this is less than $250

x =6, y= 500(0.9)^6 = 265.721 ≈ 265.72, this is more than $250

What is being asked in the problem and what does that mean?

We are asked to find the value of x that represents the years such that the value of the console is still under $250.

What do I know and what does it mean? What plan am I going to try?

We know the value of y has to be less that $250, we know the inequality

[500(.9)^x ] < 250, the plan is to try different values for x until we have the maximum value of x that gives us less than 250.

8 0
3 years ago
Your schools talent show will feature 12 solo acts and ensemble 2 acts. The show will last 90 min. The 6 solo performers judged
kicyunya [14]
A.  12*x + 2*y = 90
       6*x + 2*y = 60

To write system of equation you just need to sum all solo and ensemble acts and make it equal to how much they will last for.

B.  Here we can multiply second equation with negative 1 and add it to first equation.
6x = 30
x = 5

now we replace x in any of 2 equations to get y.
30+2y = 60
2y = 30
y=15

Solo acts are 5 minutes long and ensemble acts are 15 minutes long
3 0
3 years ago
How to solve x(x-3)=0
damaskus [11]

Step-by-step explanation:

x(x-3)=0

x=0 or (x-3) =0

x= 0 or x =3

7 0
3 years ago
I need help on number 6
Alona [7]
275 kg of copper. C.
4 0
3 years ago
Help!! 30 points!!
erica [24]

Answer:

a. 47.6mph (distance divided by time = speed. divide each rowers distance by their speed, then add them all)

b. 1.26 minutes per mile (i used a calculator so i dunno how to explain)

let me know if this is right or not :)

6 0
3 years ago
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