You would use the equation pi times radius to the second ( radius times radius) times height to get 4,710
The correct answer is k=6.03968419. Hope this helps! ;D

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.
The formula for simple interest is <em>I</em> = <em>prt</em>, where <em>I </em>is the amount of interest, <em>p</em> is the principal invested, <em>r</em> is the rate as a decimal number and <em>t</em> is the amount of time. Substituting our given information we have
128 = <em>p</em>(0.016)(2) ----- 1.6% = 1.6/100 = 0.016
128 = <em>p</em>(0.032)
Divide both sides by 0.032:
128/0.032 = <em>p</em>(0.032)/0.032
4000 = <em>p</em>
He needs to invest $4000.