Math  /  Algebra

QuestionGiven y=xx1y = \frac{x}{x-1} and x>1x > 1, which of the following is a possible value of yy?
A. 1.9-1.9 B. 0.9-0.9 C. 0.00.0 D. 0.90.9 E. 1.91.9

Studdy Solution

STEP 1

What is this asking? If xx is greater than 1, what are the possible values of yy when y=xx1y = \frac{x}{x-1}? Watch out! Don't forget that xx *cannot* equal 1, because that would make the denominator zero, and we can't divide by zero!

STEP 2

1. Analyze the function
2. Explore extreme cases
3. Evaluate the options

STEP 3

Let's **rewrite** our function y=xx1y = \frac{x}{x-1} in a more insightful way!
We can **add zero** in the numerator as x=x1+1x = x - 1 + 1, so y=x1+1x1y = \frac{x - 1 + 1}{x-1}.

STEP 4

Now, we can **split** the fraction: y=x1x1+1x1y = \frac{x-1}{x-1} + \frac{1}{x-1}.
This simplifies to y=1+1x1y = 1 + \frac{1}{x-1}.
Much better!

STEP 5

Since x>1x > 1, we know that x1>0x - 1 > 0.
This means 1x1\frac{1}{x-1} will *always* be **positive**.

STEP 6

Therefore, y=1+1x1y = 1 + \frac{1}{x-1} will *always* be **greater than 1**.

STEP 7

What happens when xx gets really, really close to 1?
Let's imagine x=1.000001x = 1.000001.
Then x1=0.000001x - 1 = 0.000001, and 1x1=10.000001=1,000,000\frac{1}{x-1} = \frac{1}{0.000001} = 1,000,000.
So y=1+1,000,000=1,000,001y = 1 + 1,000,000 = 1,000,001! yy gets **super huge**!

STEP 8

What if xx is gigantic, like x=1,000,001x = 1,000,001?
Then x1=1,000,000x - 1 = 1,000,000, and 1x1=11,000,000=0.000001\frac{1}{x-1} = \frac{1}{1,000,000} = 0.000001.
So y=1+0.000001=1.000001y = 1 + 0.000001 = 1.000001. yy gets really **close to 1**!

STEP 9

We know yy must be greater than 1.
Looking at our options, only one value is greater than 1: **1.9**.

STEP 10

The answer is E. yy can be **1.9**.

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