What is it ?:( help please
2 answers:
Answer:
You got the first two correct, both negatives. But, number 15 is a positive.
Step-by-step explanation:
3)
ex.
In order to receive a positive at the end, the second step's (-1) needs to be placed with (+1).
Of course, the positive sign doesn't need to be put in front of the one, it is just used for visual purposes.
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Carry out the binomial expansion in the numerator:
Then the 9⁴ terms cancel each other, so in the limit we have
Since <em>h</em> is approaching 0, that means <em>h</em> ≠ 0, so we can cancel the common factor of <em>h</em> in both numerator and denominator:
Then when <em>h</em> converges to 0, each remaining term containing <em>h</em> goes to 0, leaving you with
or choice C.
Alternatively, you can recognize the given limit as the derivative of <em>f(x)</em> at <em>x</em> = 9:
We have <em>f(x)</em> = <em>x</em> ⁴, so <em>f '(x)</em> = 4<em>x</em> ³, and evaluating this at <em>x</em> = 9 gives the same result, 2916.