vertical asymptotes

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July 6th 2006, 04:24 PM
Lane

pretest 6 math questions

Find the horizontal asymptote of the graph f(x)= 2/x-4

A: y=2 B: x=0 C: x=4 D: y=0

Find the vertical asymptote(s) if any, for f(x)= 4x-4/x2-5x-6

A: x=-1, x=6, x=4 B: x=-1, x=6 C: x=4, x=-1 D: none

Find the zeros of the function. F(x)= 4x-7/x-2
July 6th 2006, 06:09 PM
ThePerfectHacker

Quote:

Originally Posted by Lane

Find the horizontal asymptote of the graph f(x)= 2/x-4

A: y=2 B: x=0 C: x=4 D: y=0

At this level it is when the denominator is zero. Thus, if you mean $y=\frac{2}{x}-4$ then the answer is $x=0$ and if you mean $y=\frac{2}{x-4}$ then the answer is $x=4$

Quote:

Originally Posted by Lane

Find the vertical asymptote(s) if any, for f(x)= 4x-4/x2-5x-6

A: x=-1, x=6, x=4 B: x=-1, x=6 C: x=4, x=-1 D: none

Factor
$\frac{4(x-1)}{(x+1)(x-6)}$ that happens when $x=-1,6$ (remember set each factor equal to zero).

Quote:

Originally Posted by Lane

Find the zeros of the function. F(x)= 4x-7/x-2

You need an "x" such as,
$\frac{4x-7}{x-2}$ a fraction is only zero when its numerator is zero thus,
$4x-7=$ thus, $x=7/4=1.75$
July 7th 2006, 06:56 AM
earboth

Quote:

Originally Posted by Lane

Find the horizontal asymptote of the graph f(x)= 2/x-4

A: y=2 B: x=0 C: x=4 D: y=0...

Hello,Lane,

you'll get the horizontal asymptote if calculate the limit of f(x):

a) you mean: $f(x)=\frac{2}{x}-4$ . Then $\lim_\csub{|x|\rightarrow\infty} f(x)=-4\ \Longrightarrow\ As: y = -4$

b) you mean: $f(x)=\frac{2}{x-4}$ . then $\lim_\csub{|x|\rightarrow\infty} f(x)=0\ \Longrightarrow\ As: y = 0$

The possible answers doesn't include y = -4, therefore the answer is D.

Greetings

EB