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3 years ago

What value for C will make the expression a perfect square trinomial x2-7x+c

Mathematics

2 answers:

Tom [10]3 years ago

7 0

Answer:

The value of c is 12.25

Step-by-step explanation:

we know that

A perfect square trinomial is of the form

$(x-a)^{2}=x^{2}-2ax+a^{2}$

In this problem we have

$x^{2}-7x+c$

equate the equations

$x^{2}-7x+c=x^{2}-2ax+a^{2}$

we have

the following equations

$-7x=-2ax$ -----> equation A

and

$c=a^{2}$ -----> equation B

<u>Solve the equation A</u>

$-7x=-2ax$

$7=2a$

$a=3.5$

<u>Solve the equation B</u>

$c=a^{2}$

$c=3.5^{2}=12.25$

therefore

$(x-3.5)^{2}=x^{2}-7x+12.25$

The value of c is 12.25

wlad13 [49]3 years ago

3 0

Answer:

49/4

Step-by-step explanation:

To make x2-7x+c a perfect square trinomial we do it by completing the square method. First, make half of the coefficient of x then add and subtract by squaring it. c=49/4 this is the required value of c.

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A certain flight arrives on time 8484 percent of the time. Suppose 143143 flights are randomly selected. Use the normal approxim

Troyanec [42]

Answer:

a) P(x=108)=0.0020

b) P(x≥108)=0.9980

c) P(x<124)=0.7794

d) P(124≤x≤128)=0.1925

Step-by-step explanation:

We know the population proportion, that is p=0.84.

We take a sample of size n=143.

We will use the normal approximation to the binomial distribution to model this problem.

The mean and standard deviation of the normal approximation to the binomial distribution will be:

$\mu=np=143*0.84=120.12\\\\\sigma=\sqrt{np(1-p)}=\sqrt{143*0.84*0.16}=\sqrt{19.22}=4.38$

a) We have to calculate the probability that exactly 108 flights are on time.

As the normal distribution considers the random variable to be continous, we have to apply the continuity correction factor.

In this case, the probability of 108 flights on time can be calculated as P(107.5<x<108.5):

$P(x=108)=P(107.5$

b) Now we have to calculate that at least 108 flights are on time.

As the probability includes 108, the continuity factor will indicates that we calculate P(x>107.5). The z-value for x=107.5 has been already calculated in point a:

$P(x\geq108)=P(x>107.5)=P(z>-2.88)=0.9980$

c) We have to calculate the probability that fewer than 124 flights are on time. According to the continuity factor, we have to calculate the probability P(x<123.5), as the flight number 124 is not included in the interval.

$P(x$