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3 years ago

Solve the equation 5+7 | 2x-1 | = -44

Mathematics

1 answer:

dlinn [17]3 years ago

3 0

The easy part is isolating the absolute-value term:

5 + 7 |2x - 1| = -44

7 |2x - 1| = -49

|2x - 1| = -7

Remember that the absolute value function returns a positive number that you can think of as the "size" of that number, or the positive distance between that number and zero. If x is a positive number, its absolute value is the same number, |x| = x. But if x is negative, then the absolute value returns its negative, |x| = -x, which makes it positive. (If x = 0, you can use either result, since -0 is still 0.)

The important thing to take from this is that there are 2 cases to consider: is the expression in the absolute value positive, or is it negative?

• If 2x - 1 > 0, then |2x - 1| = 2x - 1. Then the equation becomes

2x - 1 = -7

2x = -6

x = -3

• If 2x - 1 < 0, then |2x - 1| = - (2x - 1) = 1 - 2x. Then

1 - 2x = -7

-2x = -8

x = 4

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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,

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Let us convert our given rate in decimal form.

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

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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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