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3 years ago

the distance around a track is 400m. if you take 14 laps around the track what is the total distance you walk? use mental math

Mathematics

2 answers:

Olegator [25]3 years ago

6 0

to do it in mental math: you can ignore the zeroes in 400 for now.

4*14 = 4*10 + 4*4 = 40 + 16 = 56

now add the zeroes back on: 5600m

harkovskaia [24]3 years ago

3 0

Well, if you go around the track once, that's 400m. Going around the track once is one lap. So, if you went around 14 times, that would be going 400m each time. In your head, you would find the product of 14 and 400, which would be 5600m. Your total distance would be 5600m.

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3 years ago

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Determine the singular points of the given differential equation. Classify each singular point as regular or irregular. (Enter y

ludmilkaskok [199]

Answer:

Step-by-step explanation:

Given that:

The differential equation; $(x^2-4)^2y'' + (x + 2)y' + 7y = 0$

The above equation can be better expressed as:

$y'' + \dfrac{(x+2)}{(x^2-4)^2} \ y'+ \dfrac{7}{(x^2- 4)^2} \ y=0$

The pattern of the normalized differential equation can be represented as:

y'' + p(x)y' + q(x) y = 0

This implies that:

$p(x) = \dfrac{(x+2)}{(x^2-4)^2} \$

$p(x) = \dfrac{(x+2)}{(x+2)^2 (x-2)^2} \$

$p(x) = \dfrac{1}{(x+2)(x-2)^2}$

Also;

$q(x) = \dfrac{7}{(x^2-4)^2}$

$q(x) = \dfrac{7}{(x+2)^2(x-2)^2}$

From p(x) and q(x); we will realize that the zeroes of (x+2)(x-2)² = ±2

When x = - 2

$\lim \limits_{x \to-2} (x+ 2) p(x) = \lim \limits_{x \to2} (x+ 2) \dfrac{1}{(x+2)(x-2)^2}$

$\implies \lim \limits_{x \to2} \dfrac{1}{(x-2)^2}$

$\implies \dfrac{1}{16}$

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$\implies \lim \limits_{x \to2} \dfrac{7}{(x-2)^2}$

$\implies \dfrac{7}{16}$

Hence, one (1) of them is non-analytical at x = 2.

Thus, x = 2 is an irregular singular point.

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3 years ago

You purchase a stereo system for $830. The value of the stereo system decreases 13% each year. a. Write an exponential decay mod

lorasvet [3.4K]

Answer:

a. $y=830*(0.87)^x$

b. The value of stereo system after 2 years will be $628.23.

c. After approximately 4.98 years the stereo will be worth half the original value.

Step-by-step explanation:

Let x be the number of years.

We have been given that you purchased a stereo system for $830. The value of the stereo system decreases 13% each year.

a. Since we know that an exponential function is in form: $y=a*b^x$ , where,

a = Initial value,

b = For decay b is in form (1-r), where r is rate in decimal form.

Let us convert our given rate in decimal form.

$13\%=\frac{13}{100}=0.13$

Upon substituting our given values in exponential decay function we will get

$y=830*(1-0.13)^x$

$y=830*(0.87)^x$

Therefore, the exponential model $y=830*(0.87)^x$ represents the value of the stereo system in terms of the number of years since the purchase.

b. To find the value of stereo system after 2 years we will substitute x=2 in our model.

$y=830*(0.87)^2$

$y=830*0.7569$

$y=628.227\approx 628.23$

Therefore, the value of stereo system after 2 years will be $628.23.

c. The half of the original price will be $\frac{830}{2}=415$ .

Let us substitute y=415 in our model to find the time it will take the stereo to be worth half the original value.

$415=830*(0.87)^x$

Upon dividing both sides of our equation by 830 we will get,

$\frac{415}{830}=\frac{830*(0.87)^x}{830}$

$0.5=0.87^x$

Let us take natural log of both sides of our equation.

$ln(0.5)=ln(0.87^x)$

Using natural log property $ln(a^b)=b*ln(a)$ we will get,

$ln(0.5)=x*ln(0.87)$

$\frac{ln(0.5)}{ln(0.87)}=\frac{x*ln(0.87)}{ln(0.87)}$

$\frac{ln(0.5)}{ln(0.87)}=x$

$\frac{-0.6931471805599}{-0.139262067}=x$

$x=4.977286\approx 4.98$

Therefore, after approximately 4.98 years the stereo will be worth half the original value.

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3 years ago

HELP When 2((Three-fifths x + 2 and three-fourths y minus one-fourth x minus 1 and one-half y + 3)) is simplified, what is the r

lesya692 [45]

Answer:

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Step-by-step explanation:

Given the expression $2(\frac{3x}{5}+2\frac{3y}{4}-\frac{x}{4}-1 \frac{1}{2}y+3)$

To simplify the expression, we need to first collect the like terms of the functions in parentheses as shown;

$= 2(\frac{3x}{5}-\frac{x}{4}-1 \frac{1}{2}y+2\frac{3}{4}y+3)\\= 2(\frac{3x}{5}-\frac{x}{4}- \frac{3}{2}y+\frac{11}{4}y+3)\\$

Then we find the LCM of the resulting function

$= 2(\frac{3x}{5}-\frac{x}{4}- \frac{3}{2}y+\frac{11}{4}y+3)\\= 2(\frac{12x-5x}{20} - (\frac{6y-11y}{4})+3)\\= 2(\frac{7x}{20}- (\frac{-5y}{4})+3 )\\= 2(\frac{7x}{20}+ \frac{5y}{4}+3 )\\= \frac{7x}{10} + \frac{5y}{2} +6\\= \frac{7x}{10} + 2\frac{1}{2}y+6\\$

The final expression gives the required answer

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2 years ago