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? asked in Science & MathematicsMathematics · 8 years ago

Algebra 2 Question - Help!!?

What is the coefficient of X^5 in the expansion of (x+3)^7 ?

*PLEASE SHOW WORK*

First good answer=10 points!

2 Answers

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  • Anonymous
    8 years ago
    Favorite Answer

    x^7 + 21x^6 + 189x^5 + 945x^4 + 2835x^3 + 5103x^2 + 5103x + 2187

    So its

    189

    Don't know how to show my work as it's just the binominal expansion

    :)

  • Renie
    Lv 6
    8 years ago

    Since the power of (X+3) is 7, then the exponents will add to 7

    So x^5 * 3^2 will be the product, and the coefficient of this term will be C(7,2)

    C(7,2)= 7!/(2!5!)= 21

    21(x^5)(3^2)= 189x^5

    I hope this helps!

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