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# PreCalculus - Binomial Theorem: Find the coefficient of x^8 in the expansion (x^2+3)^7?

PreCalculus - Binomial Theorem (coefficient)

Formula: (n C n-j)*a^(n-j)*x^j

### 2 Answers

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- chauncyLv 71 decade agoBest Answer
Well in this case the formula would be

(n C n-j)*a^(n-j)*(x^2)^j

x^8 = (x^2)^4

so j = 4

n = 7

n - j = 3

a = 3

So the term that contains x^8 is

(7 C 3)*3^3*(x^2)^4

= 35*27*x^8

The coefficient of x^8 is 945.

- marciLv 43 years ago
The coefficient of x indoors the strengthen of (3x + 5)^5 (3x + 5)^5 = The coefficient of x = 5C4(3x)(5)^4 Coefficient of x = (5*4*3*2/4*3*2*a million)(3x)(625) Coefficient of x = 9375. ................ answer

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