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Only answer if you're very good at math.Please I keep on posting this but nobody is helping me.

What is the 4th term of the expansion of (1 - 2x)^n if the binomial coefficients are taken from the row of Pascal's triangle shown below?

1 6 15 20 15 6 1

A: 240x^4

B: 160x^3

C: -160x^3

D: -20x^3​


Sagot :

I believe A. but Major guess tho

The fourth term of the given expansion is [tex]-280x^{3}[/tex].

What is binomial expansion?

The binomial expansion is used to expand and write the terms which are equals to the natural number exponent of the sum or differences of two terms.

The general term of the binomial expansion is given by

[tex]T_{r+1} =nC_{r} x^{n-r} y^{r}[/tex]

According to the given question

We have,

A binomial expression, [tex](1-2x)^{n}[/tex]

and, the binomial coefficients are taken from the row of Pascal's triangle 1  6  15  20  15  6  1

n = 7

Therefore,

The fourth term of the expansion of [tex](1-2x)^{n}[/tex] is given by

[tex]T_{3+1} = 7C_{3} 1^{7-3} (-2x)^{3}[/tex]

[tex]T_{4} =\frac{(7)(6)(5)(4)(3!)}{3!(4)(3)(2)} (1)(-2x)^{3}[/tex]

[tex]T{4} = -280x^{3}[/tex]

Hence, the fourth term of the given expansion [tex](1-2x)^{3}[/tex] is [tex]-280x^{3}[/tex].

Learn more about the binomial expansion here:

https://brainly.com/question/12249986

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