# Y-intercepts of this function

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• Feb 23rd 2011, 05:48 PM
youngb11
Y-intercepts of this function
$f(x)=7(x-4)^{\frac{3}{4}} - 3(x-4)^{\frac{7}{4}}$

Do the y-intercepts exist for this function? According to wolframalpha they do, but I don't see how that's possible.
• Feb 23rd 2011, 05:58 PM
skeeter
Quote:

Originally Posted by youngb11
$f(x)=7(x-4)^{\frac{3}{4}} - 3(x-4)^{\frac{7}{4}}$

Do the y-intercepts exist for this function? According to wolframalpha they do, but I don't see how that's possible.

what did you enter into wolfram?
• Feb 23rd 2011, 05:59 PM
sa-ri-ga-ma
On the y-axis x co-ordinate is zero. So find f(x).
• Feb 23rd 2011, 06:00 PM
youngb11
Quote:

Originally Posted by skeeter
what did you enter into wolfram?

$7 (x - 4)^(3/4) - 3 (x - 4)^(7/4)$

But there are no y-intercepts, right?
• Feb 23rd 2011, 06:01 PM
youngb11
Quote:

Originally Posted by sa-ri-ga-ma
On the y-axis x co-ordinate is zero. So find f(x).

But how can you evaluate $(-4)^{\frac{3}{4}}$
• Feb 23rd 2011, 06:01 PM
skeeter
Quote:

Originally Posted by youngb11
$7 (x - 4)^(3/4) - 3 (x - 4)^(7/4)$

But there are no y-intercepts, right?

answer my question, please.
• Feb 23rd 2011, 06:03 PM
youngb11
Quote:

Originally Posted by skeeter
answer my question, please.

Exactly what I posted:

7 (x - 4)^(3/4) - 3 (x - 4)^(7/4)
• Feb 23rd 2011, 06:09 PM
Quacky
You are correct in that there are no y-intercepts. Skeeter wants you to write exactly what you entered into Wolfram: somewhere, there must have been a mistake with the way you presented your formula to Wolfram or there was a misinterpretation of the formula on WA's part.
Try writing the exponents in decimal form.