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UNO [17]
3 years ago
14

How many solutions does the system of equations x − y = 7 and y equals the square root of the quantity 3 times x plus 3 end quan

tity minus 2 have?
Mathematics
1 answer:
Alla [95]3 years ago
8 0

9514 1404 393

Answer:

  one solution (11, 4)

Step-by-step explanation:

Both equations describe curves with positive slope. The y-intercept of the line (-7) is less than that of the root function (-2), so the line must intersect the root function in exactly one place. There is one solution.

__

Solved in the conventional way, the equation would become a quadratic, with two solutions. One of them is extraneous. (That is why I prefer a graphical solution.)

Given ...

  x -y = 7

  y = √(3x +3) -2

We can substitute for y to get ...

  x -7 = √(3x +3) -2

  x -5 = √(3x +3)

  x^2 -10x +25 = 3x +3 . . . . . . square both sides

  x^2 -13x +22 = 0 = (x -11)(x -2) . . . . . gives solutions x=11, x=2

The value x=2 does not satisfy the equation ...

  x -7 = √(3x +3) -2   ⇒   2 -7 = √(3·2 +3) -2   ⇒   -5 = 1 (false)

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3 years ago
A battery has a lifetime that is approximately normally distributed with a mean of 600 hours and a standard deviation of 50 hour
miss Akunina [59]

Answer:

A. Your battery is likely defective since such poor performance is extremely unlikely.

Step-by-step explanation:

When the distribution is normal, we use the z-score formula.

In a set with mean \mu and standard deviation \sigma, the zscore of a measure X is given by:

Z = \frac{X - \mu}{\sigma}

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

If X is more than two standard deviations from the mean, it is considered an unlikely outcome.

In this question, we have that:

\mu = 600, \sigma = 50

Which of the following conclusions is the most appropriate given this information?

Lasted 400 hours, so X = 400.

Z = \frac{X - \mu}{\sigma}

Z = \frac{400 - 600}{50}

Z = -4

4 standard deviations from the mean, so unlikely.

So the correct answer is:

A. Your battery is likely defective since such poor performance is extremely unlikely.

3 0
3 years ago
A rectangular parking lot has an area of 15,000 feet squared, the length is 20 feet more than the width. Find the dimensions
faust18 [17]

Dimension of rectangular parking lot is width = 112.882 feet and length = 132.882 feet

<h3><u>Solution:</u></h3>

Given that  

Area of rectangular parking lot = 15000 square feet

Length is 20 feet more than the width.

Need to find the dimensions of rectangular parking lot.

Let assume width of the rectangular parking lot in feet be represented by variable "x"

As Length is 20 feet more than the width,

so length of rectangular parking plot = 20 + width of the rectangular parking plot

=> length of rectangular parking plot = 20 + x = x + 20

<em><u>The area of rectangle is given as:</u></em>

\text {Area of rectangle }=length \times width

Area of rectangular parking lot = length of rectangular parking plot \times width of the rectangular parking

\begin{array}{l}{=(x+20) \times (x)} \\\\ {\Rightarrow \text { Area of rectangular parking lot }=x^{2}+20 x}\end{array}

But it is given that Area of rectangular parking lot = 15000 square feet

\begin{array}{l}{=>x^{2}+20 x=15000} \\\\ {=>x^{2}+20 x-15000=0}\end{array}

Solving the above quadratic equation using quadratic formula

<em><u>General form of quadratic equation is  </u></em>

{ax^{2}+\mathrm{b} x+\mathrm{c}=0

And quadratic formula for getting roots of quadratic equation is

x=\frac{-b \pm \sqrt{b^{2}-4 a c}}{2 a}

In our case b = 20, a = 1 and c = -15000

Calculating roots of the equation we get

\begin{array}{l}{x=\frac{-(20) \pm \sqrt{(20)^{2}-4(1)(-15000)}}{2 \times 1}} \\\\ {x=\frac{-(20) \pm \sqrt{400+60000}}{2 \times 1}} \\\\ {x=\frac{-(20) \pm \sqrt{60400}}{2}} \\\\ {x=\frac{-(20) \pm 245.764}{2 \times 1}}\end{array}

\begin{array}{l}{=>x=\frac{-(20)+245.764}{2 \times 1} \text { or } x=\frac{-(20)-245.764}{2 \times 1}} \\\\ {=>x=\frac{225.764}{2} \text { or } x=\frac{-265.764}{2}} \\\\ {=>x=112.882 \text { or } x=-132.882}\end{array}

As variable x represents width of the rectangular parking lot, it cannot be negative.

=> Width of the rectangular parking lot "x" = 112.882 feet  

=> Length of the rectangular parking lot = x + 20 = 112.882 + 20 = 132.882

Hence can conclude that dimension of rectangular parking lot is width = 112.882 feet and length = 132.882 feet.

3 0
3 years ago
Can you help me in write the perimeter of the triangle in a simplest form
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2x+3x+x/1x=6x

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