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Nataliya [291]
2 years ago
5

How many times does X squared minus 4X -12 cross the X axis

Mathematics
1 answer:
kolbaska11 [484]2 years ago
4 0

We can solve this problem using discriminant.

x^2-4x-12's discriminant is

(-4)^2-4*-12=16+48 which is clearly larger than 0

This means that it crosses over the axes 2 times.

In case you don't know what discriminant is, its in equation ax^2+bx+c

the discriminant is b^2-4ac.

If its positive it has 2 crosses with x axis, if negative then 0 crosses, if 0 then 1 cross.

Hope this helped at least a little bit :D

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If 2x+y=8 and x-1=y then what is y? Please be detailed I want to know more then just the answer but how to solve
IgorLugansk [536]
This is Bridge Algebra 2 stuff. Well you see that 2x+y=8 and x-1=y. To slove for y you have to slove for x first to find y. So 2x+x-1=8 ( the reason I did that is because there is a y in that equation and I placed it on that equation) now lets slove this equation for x. So 3x-1=8( I add 2x with x) 3x=9 ( I made -1 a positive one and add it to 8) x=3 ( I divided 9/3 to get 3). Now that you have slove x we will use x to slove for y. So 3-1=y, 2=y. Your answer is y=2.
4 0
3 years ago
An environmental group conducted a study to determine whether crows in a certain region were ingesting food containing unhealthy
nydimaria [60]

Part A

Given info:

  • xbar = sample mean = 4.90 ppm
  • s = sample standard deviation = 1.12 ppm
  • n = 23 = sample size

Because n > 30 is not true, and we don't know the population standard deviation (sigma), this means we must use a T distribution.

The degrees of freedom here are n-1 = 23-1 = 22.

At 90% confidence and the degrees of freedom mentioned, the t critical value is roughly t = 1.717

Use a T distribution table or calculator to determine this. If you don't have a calculator for the task, then you can search out "inverse T calculator" and there are tons of free options to pick from.

The margin of error E is

E = t*s/sqrt(n)

E = 1.717*1.12/sqrt(23)

E = 0.400982

This is approximate and accurate to 6 decimal places.

The confidence interval is going to be xbar plus or minus that E value

L = lower bound = xbar - E = 4.90 - 0.400982 = 4.499018 = 4.50

U = upper bound = xbar + E = 4.90 + 0.400982 = 5.300982 = 5.30

The confidence interval in the format of (L, U) is (4.50, 5.30)

You could also express it as the format L < mu < U and it would be 4.50 < mu < 5.30; however, I'll stick to the first method.

<h3>Answer:  (4.50, 5.30)</h3>

=====================================================

Part B

Since we know sigma = 2.6 is the population standard deviation, we can use a Z distribution now.

At 90% confidence, the z critical value is roughly 1.645; use a table or calculator to determine this.

n = \left(\frac{z*\sigma}{E}\right)^2\\\\n \approx \left(\frac{1.645*2.6}{0.03}\right)^2\\\\n \approx 20325.254444 \\\\

Round this up to the nearest integer to get 20326. For min sample size problems, <u>always</u> round up.

<h3>Answer: 20326</h3>
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2 years ago
A pearl is formed in 1 of every 10,000 oysters. What percent of oysters make pearls? Hint: An answer of 1, percent would mean 1
zysi [14]
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3 0
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A fair coin is tossed twice in succession. The set of equally likely outcomes is {HH, HT, TH, TT}. What is the probability of ge
djverab [1.8K]
The probability is 1/4
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Probability of second tails = 1/2
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5 0
2 years ago
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Somebody help and explain!!!
Maslowich

Answer: The midpoint of segment PQ is the number 2.5

note: 2.5 as a fraction is 5/2; as a mixed number 2.5 converts to 2&1/2

============================================================

Explanation:

Apply the midpoint formula to get the midpoint of -8 and 6

We simply add up the values and divide by 2 and we get (-8+6)/2 = -2/2 = -1

So point Q is at -1 on the number line, which is exactly halfway from R to P

Focus on just points P and Q now. Apply the midpoint formula again

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So the midpoint of segment PQ is 2.5

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