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3 years ago

Determine the exact value of k so that the quadratic function f(x) = x2 - kx + 5 has only one zero.

2 answers:

6 0

I like this question. When we factorise this question the brackets have to be identical.
5 has to be square rooted to become √5. From, FOIL we know that the last digit is times by the other last digit to find the 5, as our brackets are identical this number is the same. The square root of 5.
This number is doubled in identical brackets to find the middle number. so it is 2√5. As there is a minus number there the brackets are: (x-√5)(x-√5). Multiplying this out gives us: x²-2√5 x+5. k=2√5 (or -2√5, depending on if the minus is counted or not)

JulsSmile [24]3 years ago

3 0

$f(x)=ax^2+bx+c\\\\\Delta=b^2-4ac\\\\if\ \Delta < 0-no\ zeros\\if\ \Delta=0-one\ zero\\if\ \Delta > 0-two\ zeros$

$f(x)=x^2-kx+5=0\\\\a=1;\ b=-k;\ c=5\\\\\Delta=(-k)^2-4\cdot1\cdot5=k^2-20\\\\one\ zero\ if\ \Delta=0\\\\therefore\\k^2-20=0\ \ \ \ |add\ 20\ to\ both\ sides\\\\k^2=20\\\\k=\pm\sqrt{20}\\\\k=\pm\sqrt{4\cdot5}\\\\\boxed{k=-2\sqrt5\ or\ k=2\sqrt5}$

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Given a population with a mean of muμequals=100100 and a variance of sigma squaredσ2equals=3636, the central limit theorem appl

lakkis [162]

Answer:

a) $\bar X \sim N(100,\frac{6}{\sqrt{25}}=1.2)$

$\mu_{\bar X}=100$ $\sigma^2_{\bar X}=1$

b) $P(\bar X >101)=1-P(\bar X$

c) $P(\bar X$

Step-by-step explanation:

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".

The central limit theorem states that "if we have a population with mean μ and standard deviation σ and take sufficiently large random samples from the population with replacement, then the distribution of the sample means will be approximately normally distributed. This will hold true regardless of whether the source population is normal or skewed, provided the sample size is sufficiently large".

The complement rule is a theorem that provides a connection between the probability of an event and the probability of the complement of the event. Lat A the event of interest and A' the complement. The rule is defined by: $P(A)+P(A') =1$

Let X the random variable that represent the variable of interest on this case, and for this case we know the distribution for X is given by:

$X \sim N(\mu=100,\sigma=6)$

And let $\bar X$ represent the sample mean, by the central limit theorem, the distribution for the sample mean is given by:

$\bar X \sim N(\mu,\frac{\sigma}{\sqrt{n}})$

a. What are the mean and variance of the sampling distribution for the sample means?

$\bar X \sim N(100,\frac{6}{\sqrt{25}}=1.2)$

$\mu_{\bar X}=100$ $\sigma^2_{\bar X}=1.2^2=1.44$

b. What is the probability that x overbarxgreater than>101

First we can to find the z score for the value of 101. And in order to do this we need to apply the formula for the z score given by:

$z=\frac{x-\mu}{\frac{\sigma}{\sqrt{n}}}$

If we apply this formula to our probability we got this:

$z=\frac{101-100}{\frac{6}{\sqrt{25}}}=0.833$

And we want to find this probability:

$P(\bar X >101)=1-P(\bar X$

On this last step we use the complement rule.

c. What is the probability that x bar 98less than

First we can to find the z score for the value of 98.

$z=\frac{98-100}{\frac{6}{\sqrt{25}}}=-1.67$

And we want to find this probability:

$P(\bar X$

5 0

4 years ago

If ∠GHJ≅∠IHJ and GJ=99, what is IJ?

quester [9]

Answer:

Step-by-step explanation:

Triangles GJH and IJH are congruent, so GJ=IJ=99.

6 0

2 years ago

My question is in the attachment.<br>

Nikolay [14]

Answer:

5 and 25

Step-by-step explanation:

let the son's age be x then the father's age is x + 20

In 5 years

son = x + 5 and father = x + 20 + 5 = x + 25

Then

x + 25 = 3(x + 5) ← father is three times as old as son

x + 25 = 3x + 15 ( subtract x from both sides )

25 = 2x + 15 ( subtract 15 from both sides )

10 = 2x ( divide both sides by 2 )

5 = x and x + 20 = 5 + 20 = 25

si=on is 5 and father is 25

8 0

3 years ago

Read 2 more answers

Find the difference 10 - ( – 25 )

sergey [27]

There is no difference they are both negative numbers or we could say 25 is higher number then 10 but it negative

5 0

3 years ago

Read 2 more answers

15 people received an email and sent it to 3 different friends each, who in turn sent it to 2 new people. What percent of the to

masya89 [10]

Step 1: Multiply 15 by 3, which equals 45.
Step 2: Multiply 45 by 2, which gives you 90.
Step 3: Add everything up. 15 + 90 + 45 is 150
Step 4: Find the percent of 15 people in a group of 150 people by diving 150 by 15.

150 / 15 = 10.

FINAL ANSWER: 10%

6 0

3 years ago