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Letf(x) = \frac{3x - 7}{x + 1}.Find the range of f. Give your answer as an interval. 

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 Nov 6, 2014

Best Answer 

 #1
avatar+23254 
+8

When graphed, this is a hyperbola. The question is:  What y-value is impossible?

If you find the lim(x→∞) [3x - 7] / [x + 1], you will be able to answer the question.

Rewrite  [3x - 7] / [x + 1]  =  [3 - 7/x] / [1 + 1/x]   (by dividing all terms by x0

--->    lim(x→∞) [3 - 7/x] / [1 + 1/x]  =  3.

To show that 3 is impossible, try to solve the equation:  3  =  (3x - 7) / (x + 1)

     Multiply both sides by  x + 1     --->     3(x + 1)  =  3x - 7     --->     3x + 3  =  3x - 7

     --->  3  =  -7   Impossible!

Thus, the range is all numbers but 3.

 Nov 6, 2014
 #1
avatar+23254 
+8
Best Answer

When graphed, this is a hyperbola. The question is:  What y-value is impossible?

If you find the lim(x→∞) [3x - 7] / [x + 1], you will be able to answer the question.

Rewrite  [3x - 7] / [x + 1]  =  [3 - 7/x] / [1 + 1/x]   (by dividing all terms by x0

--->    lim(x→∞) [3 - 7/x] / [1 + 1/x]  =  3.

To show that 3 is impossible, try to solve the equation:  3  =  (3x - 7) / (x + 1)

     Multiply both sides by  x + 1     --->     3(x + 1)  =  3x - 7     --->     3x + 3  =  3x - 7

     --->  3  =  -7   Impossible!

Thus, the range is all numbers but 3.

geno3141 Nov 6, 2014

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