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2 years ago

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Kyle's math teacher is basing quarterly grades on different percentages for the various work shown on the table. Using the given

scores, what is Kyle's expected quarterly average? Round to the nearest whole percent.

1 answer:

Xelga [282]2 years ago

6 0

Kyles expected quarterly average is 87%

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Solve the recurrence relation: hn = 5hn−1 − 6hn−2 − 4hn−3 + 8hn−4 with initial values h0 = 0, h1 = 1, h2 = 1, and h3 = 2 using (

musickatia [10]

(a) Suppose $h_n=r^n$ is a solution for this recurrence, with $r\neq0$ . Then

$r^n=5r^{n-1}-6r^{n-2}-4r^{n-3}+8r^{n-4}$
$\implies1=\dfrac5r-\dfrac6{r^2}-\dfrac4{r^3}+\dfrac8{r^4}$
$\implies r^4-5r^3+6r^2+4r-8=0$
$\implies (r-2)^3(r+1)=0\implies r=2,r=-1$

So we expect a general solution of the form

$h_n=c_1(-1)^n+(c_2+c_3n+c_4n^2)2^n$

With $h_0=0,h_1=1,h_2=1,h_3=2$ , we get four equations in four unknowns:

$\begin{cases}c_1+c_2=0\\-c_1+2c_2+2c_3+2c_4=1\\c_1+4c_2+8c_3+16c_4=1\\-c_1+8c_2+24c_3+72c_4=2\end{cases}\implies c_1=-\dfrac8{27},c_2=\dfrac8{27},c_3=\dfrac7{72},c_4=-\dfrac1{24}$

So the particular solution to the recurrence is

$h_n=-\dfrac8{27}(-1)^n+\left(\dfrac8{27}+\dfrac{7n}{72}-\dfrac{n^2}{24}\right)2^n$

(b) Let $G(x)=\displaystyle\sum_{n\ge0}h_nx^n$ be the generating function for $h_n$ . Multiply both sides of the recurrence by $x^n$ and sum over all $n\ge4$ .

$\displaystyle\sum_{n\ge4}h_nx^n=5\sum_{n\ge4}h_{n-1}x^n-6\sum_{n\ge4}h_{n-2}x^n-4\sum_{n\ge4}h_{n-3}x^n+8\sum_{n\ge4}h_{n-4}x^n$
$\displaystyle\sum_{n\ge4}h_nx^n=5x\sum_{n\ge3}h_nx^n-6x^2\sum_{n\ge2}h_nx^n-4x^3\sum_{n\ge1}h_nx^n+8x^4\sum_{n\ge0}h_nx^n$
$G(x)-h_0-h_1x-h_2x^2-h_3x^3=5x(G(x)-h_0-h_1x-h_2x^2)-6x^2(G(x)-h_0-h_1x)-4x^3(G(x)-h_0)+8x^4G(x)$
$G(x)-x-x^2-2x^3=5x(G(x)-x-x^2)-6x^2(G(x)-x)-4x^3G(x)+8x^4G(x)$
$(1-5x+6x^2+4x^3-8x^4)G(x)=x-4x^2+3x^3$
$G(x)=\dfrac{x-4x^2+3x^3}{1-5x+6x^2+4x^3-8x^4}$
$G(x)=\dfrac{17}{108}\dfrac1{1-2x}+\dfrac29\dfrac1{(1-2x)^2}-\dfrac1{12}\dfrac1{(1-2x)^3}-\dfrac8{27}\dfrac1{1+x}$

From here you would write each term as a power series (easy enough, since they're all geometric or derived from a geometric series), combine the series into one, and the solution to the recurrence will be the coefficient of $x^n$ , ideally matching the solution found in part (a).

3 0

2 years ago

How do you write 2.8 millimeters in expanded form?

KengaRu [80]

2.8 millimeter to meters is .0028 but to tell you, you didn't word the question correctly at there no such thing as expanded form

3 0

2 years ago

Read 2 more answers

Help quick The engineers designing the All Aboard Railroad between Boca Raton and Jupiter decide to create parallel tracks throu

QveST [7]

Answer:

Do you have answer choices

Step-by-step explanation:

8 0

2 years ago

A falcon flying 55 mph crosses a lake in 1 minute. How long would it take a hummingbird flying 45 mph to cross the same lake?

OverLord2011 [107]

Answer:

1 2/9 minutes

Step-by-step explanation:

55 mph

55 / 60 = 11/12

11/12 of a mile = 1 minute

45 mph

45 / 60 = 3/4

3/4 of a mile = 1 minute

11/12 divided by 3/4

11/12 * 4/3

We can cross-cancel

11/3 * 1/3 = 11/9 = 1 2/9

It takes 1 2/9 minutes for the hummingbird to cross the lake

Hope this helps!

(Please let me know if I did something wrong!)

7 0

2 years ago

Read 2 more answers

What values of c and d make the equation true? RootIndex 3 StartRoot 162 x Superscript c Baseline y Superscript 5 Baseline EndRo

Reil [10]

Answer:

<em>c=6, d=2</em>

Step-by-step explanation:

<em>Equations </em>

We must find the values of c and d that make the below equation be true

$\sqrt[3]{162x^cy^5}=3x^2y \sqrt[3]{6y^d}$

Let's cube both sides of the equation:

$\left (\sqrt[3]{162x^cy^5}\right )^3=\left (3x^2y \sqrt[3]{6y^d}\right)^3$

The left side just simplifies the cubic root with the cube:

$162x^cy^5=\left (3x^2y \sqrt[3]{6y^d}\right)^3$

On the right side, we'll simplify the cubic root where possible and power what's outside of the root:

$162x^cy^5=3^3x^6y^3 (6y^d)$

Simplifying

$x^cy^5=x^6y^{3+d}$

Equating the powers of x and y separately we find

c=6

5=3+d

d=2

The values are

$\boxed{c=6,d=2}$

3 0

2 years ago

Read 2 more answers