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Andru [333]
2 years ago
13

Let f(x) = cxe−x2 if x ≥ 0 and f(x) = 0 if x < 0.

Mathematics
1 answer:
sergij07 [2.7K]2 years ago
5 0

(a) If <em>f(x)</em> is to be a proper density function, then its integral over the given support must evaulate to 1:

\displaystyle\int_{-\infty}^\infty f(x)\,\mathrm dx = \int_0^\infty cxe^{-x^2}\,\mathrm dx=1

For the integral, substitute <em>u</em> = <em>x</em> ² and d<em>u</em> = 2<em>x</em> d<em>x</em>. Then as <em>x</em> → 0, <em>u</em> → 0; as <em>x</em> → ∞, <em>u</em> → ∞:

\displaystyle\frac12\int_0^\infty ce^{-u}\,\mathrm du=\frac c2\left(\lim_{u\to\infty}(-e^{-u})-(-1)\right)=1

which reduces to

<em>c</em> / 2 (0 + 1) = 1   →   <em>c</em> = 2

(b) Find the probability P(1 < <em>X </em>< 3) by integrating the density function over [1, 3] (I'll omit the steps because it's the same process as in (a)):

\displaystyle\int_1^3 2xe^{-x^2}\,\mathrm dx = \boxed{\frac{e^8-1}{e^9}} \approx 0.3678

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azamat

Answer: i think  (4n+1)^2(4n-1)^2 isnt a multiple of 8 for all integers of n because:

(4n + 1)²(4n - 1)²

= [(4n + 1)(4n - 1)]²

= (16n² - 1)²

= 16².n².n² - 2.16.n² + 1

= 8n²(32n² - 4) + 1

can see 8n²(32n² - 4) is a multiple of 8 but 1 isnt a multiple of 8

=> (4n + 1)²(4n - 1)² isnt a multiple of 8 for all integers of n.

Step-by-step explanation:

6 0
3 years ago
Which of the following properties can numbers have?
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If y varies inversely as x and y=23 when x=8 find y when x=4
valina [46]
<h2>INVERSE VARIATION</h2>

<em>E</em><em>Q</em><em>U</em><em>A</em><em>T</em><em>I</em><em>O</em><em>N</em><em>:</em><em> </em><em> </em><em> </em><em> </em>

y =  \frac{k}{x}

<em>–</em><em>–</em><em>–</em><em>–</em><em>–</em><em>–</em><em>–</em><em>–</em>

First, find the constant of variation <em>k</em> using the formula k=xy.

23 =  \frac{k}{8}

k = (8)(23)

k = 184

<em>–</em><em>–––––––</em>

Then, find <em>y</em> if <em>x</em> is equal to four using the formula y=184/x.

y =  \frac{184}{x}

y =  \frac{184}{4}

y = 46

<em>F</em><em>i</em><em>n</em><em>a</em><em>l</em><em> </em><em>A</em><em>n</em><em>s</em><em>w</em><em>e</em><em>r</em><em>:</em>

<h2>y = 46</h2>
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mamaluj [8]

Answer:

Step-by-step explanation:

\dfrac{3}{6}=\dfrac{9}{18}=\dfrac{27}{54}

\dfrac{3*3}{6*3}=\dfrac{9}{18}\\\\\\\dfrac{3*9}{6*9}=\dfrac{27}{54}

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Step-by-step explanation:

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