How is multiplying two decimals different from multiplying one decimal by a whole number?

1 answer:

Natasha2012 [34]3 years ago

4 0

Answer: The major difference is that after you have finished multiplying all the terms (while ignoring the decimal points), you have to add up how many decimal places there are in the factors, and put that many decimal places in the answer.

Step-by-step explanation:

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1) Use power series to find the series solution to the differential equation y'+2y = 0 PLEASE SHOW ALL YOUR WORK, OR RISK LOSING

iogann1982 [59]

$y=\displaystyle\sum_{n=0}^\infty a_nx^n$

then

$y'=\displaystyle\sum_{n=1}^\infty na_nx^{n-1}=\sum_{n=0}^\infty(n+1)a_{n+1}x^n$

The ODE in terms of these series is

$\displaystyle\sum_{n=0}^\infty(n+1)a_{n+1}x^n+2\sum_{n=0}^\infty a_nx^n=0$

$\displaystyle\sum_{n=0}^\infty\bigg(a_{n+1}+2a_n\bigg)x^n=0$

$\implies\begin{cases}a_0=y(0)\\(n+1)a_{n+1}=-2a_n&\text{for }n\ge0\end{cases}$

We can solve the recurrence exactly by substitution:

$a_{n+1}=-\dfrac2{n+1}a_n=\dfrac{2^2}{(n+1)n}a_{n-1}=-\dfrac{2^3}{(n+1)n(n-1)}a_{n-2}=\cdots=\dfrac{(-2)^{n+1}}{(n+1)!}a_0$

$\implies a_n=\dfrac{(-2)^n}{n!}a_0$

So the ODE has solution

$y(x)=\displaystyle a_0\sum_{n=0}^\infty\frac{(-2x)^n}{n!}$

which you may recognize as the power series of the exponential function. Then

$\boxed{y(x)=a_0e^{-2x}}$

7 0

3 years ago

How do you find the scale factor?

Anika [276]

Answer:

The scale factor is the ratio of the length of a side of one figure to the length of the corresponding side of the other figure.

Step-by-step explanation:

6 0

3 years ago

Brown rice costs $2 per pound, and beans cost $1.60 per pound. Lin has $10 to spend on these items to make a large meal of beans

Valentin [98]

Answer:

1. $2r+1.6b=10$

2. $r=5-0.8b$

3. $b=6.25-1.25r$

Step-by-step explanation:

<h3> The complete exercise is: "Brown rice costs $2 per pound, and beans cost $1.60 per pound. Lin has $10 to spend on these items to make a large meal of beans and rice for a potluck dinner. Let b be the number of pounds of beans Lin buys and r be the number of pounds of rice she buys when she spends all her money on this meal.</h3><h3>1. Write an equation relating the two variables.</h3><h3>2. Rearrange the equation so "b" is the independent variable.</h3><h3>3. Rearrange the equation so "r" is the independent variable."</h3><h3 />

1. According to the information exercise given in the exercise, the cost per pounds of brown rice is $2. Since "r" represents the number of pounds of rice Lin buys, the total cost of the brown rice she buys can be represented with this expression:

$2r$