Find the value of "k", given that one solution of the equation x2-kx+21=0 is 3

Help please! I'm stuck with all these numbers :(

yuradex [85]

Answer:

C

Step-by-step explanation:

8 0

3 years ago

Read 2 more answers

A chess board is an 8 by 8 grid of squares. If you randomly choose 3 squares on the board, what is the probability that:

bixtya [17]

The answer is the letter B

3 0

3 years ago

Question 6 of 15

umka2103 [35]

Answer:

$LE=5\ units$

Step-by-step explanation:

we know that

In a rectangle, the two diagonals are congruent and each diagonal bisects the other

so

$LN=2KE$ ----> equation A

$KE=LE$ -----> equation B

step 1

Find the value of x

solve equation A

$LN=2KE$

substitute the given values

$(2x+2)=2(3x-7)$

solve for x

$2x+2=6x-14\\6x-2x=2+14\\4x=16\\x=4$

step 2

Find the value of KE

$KE=3x-7$

substitute the value of x

$KE=3(4)-7=5\ units$

Remember that

$KE=LE$ -----> by each diagonal bisects the other

therefore

$LE=5\ units$

8 0

3 years ago

Write an equation of the line that passes through the given point and is parallel to the given line.

9966 [12]

Answer : <em>Equation of line is</em> y=Equation of line is y= $\frac{2}{3}$ x+ $\frac{-5}{3}$

Step-by-step explanation:

Theory :

Equation of line is given as y = mx + c.

Where, m is slope and c is y intercepted.

Slope of given line : y = $\frac{2}{3}$ x+1 is m= $\frac{2}{3}$

We know that line : y = $\frac{2}{3}$ x+1 is parallel to equation of target line.

therefore, slope of target line will be $\frac{2}{3}$ .

we write equation of target line as y= $\frac{2}{3}$ x+c

Now, It is given that target line passes through point ( -5,-2)

hence, point ( -5,-2) satisfy the target line's equation.

we get,

y= $\frac{2}{3}$ x+c

-2= $\frac{2}{3}$ $\times$ -5+ c

-5= $\frac{-10}{3}$ +c

c= $\frac{-5}{3}$

thus, Equation of line is y=Equation of line is y= $\frac{2}{3}$ x+ $\frac{-5}{3}$

7 0

3 years ago

A student wanted to construct a 95% confidence interval for the mean age of students in her statistics class. She randomly selec

VMariaS [17]

Answer:

$19.1-3.355\frac{1.5}{\sqrt{9}}=17.42$

$19.1+3.355\frac{1.5}{\sqrt{9}}=20.78$

And the best option would be:

C. [17.42,20.78]

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

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".

$\bar X=19.1$ represent the sample mean

$\mu$ population mean (variable of interest)

s=1.5 represent the sample standard deviation

n=9 represent the sample size

Solution to the problem

The confidence interval for the mean is given by the following formula:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

In order to calculate the critical value $t_{\alpha/2}$ we need to find first the degrees of freedom, given by:

$df=n-1=9-1=8$

Since the Confidence is 0.99 or 99%, the value of $\alpha=0.01$ and $\alpha/2 =0.005$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.005,8)".And we see that $t_{\alpha/2}=$

Now we have everything in order to replace into formula (1):

$19.1-3.355\frac{1.5}{\sqrt{9}}=17.42$

$19.1+3.355\frac{1.5}{\sqrt{9}}=20.78$

And the best option would be:

C. [17.42,20.78]

5 0

3 years ago