We will find it as follows:
[tex]V=\frac{4}{3}\pi(x+9)^3\Rightarrow V=\frac{4\pi}{3}(x^3+27x^2+243x+729)^{}[/tex][tex]\Rightarrow V=\frac{4}{3}\pi x^3+36\pi x^2+324x+972[/tex]The volume of such a sphere is given by the expression found.
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When we have a binomial at the power of a number, of the form:
[tex](a+b)^n[/tex]We use Pascal's triangle to determine the expansion. Pascal's triangle is the following:
Each row can be used to calculate a specific power, in our case the binomial is at the power of three, and we will use the 4rth row to expand, that is:
[tex](a+b)^3=a^3+3a^2b+3ab^2+b^3[/tex]As you can see, the numbers that accompany a & b are the ones found in the 4th row of Pascal's triangle. We also see that the "degree" o the expansion always sums 3, that is a^3 has an overall degree of 3, a^2b has an overall degree of 3, ab^2 has an overall degree of 3 & b^3 has an overall degree of 3.
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If we, for example, wanted to expand (a + b)^4, we then would have the following:
*We would use the 5th row and get:
[tex](a+b)^4=a^4+4a^3b+6a^2b^2+4ab^3+b^4[/tex][Pascal's triangle expands to infinity. So, you in theory can manually expand any binomial at any power, but for big numbers, it will take a long time]
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In our case, the binomial was:
[tex](x+9)^3[/tex]And, its respective expansion is:
[tex](x+9)^3=x^3+3x^2(9)+3x(9)^2+9^3[/tex][tex]=x^3+27x^2+243x+729[/tex]
