Deriving of Binomial expansion formula for two variables (a+b)^n

in steemstem •  6 years ago 

IMG_20180620_121438_948.JPG

I explained how binomial expansion formula was derived in my last post, in case you missed it click on the link below to in to read first because this tutorial is the continuation of the previous tutorial.
Easy method to derive binomial expansion formula

The formula that was derived in the previous tutorial is for a single variable since anything raises to power 1 is equals to 1. This can't work for a two variable like (2+x)^n, (a+b)^n etc, because 2 and a will change as the power increases or decreases.

Now, let's derive the formula for the two variables using (a+ b)^n

first.png

By simplifying further,

2.png

3.png

From the knowledge of Combination that was discussed in my previous tutorial, Equation 1.1 can be rewritten as,

4.png

Substituting equation 1.4 in equation 1.0,

5.png

By opening the bracket in LHS(Left Hand Side) and RHS(Right Hand Side), then we have,

6.png

After applying the indices law, we now arrive at,

IMG_20180620_101847_272.JPG

This is how the formula was derived, in my next tutorial, some questions will be posted on binomial expansion which will be solved so that you can know the advantages of the formula.

References For Further Reading

Quora- Binomial expansion
Proof of binomial expansion

You can also read my previous tutorials:
Easy method to derive binomial expansion formula
Tutorial on Combination
Explanation on why 0!=1

Pictures: All equations were written with maths editor.

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Nice derivation of the Binomial Formula. I love the way you expressed (a+b)^b in the form [a(1+b/a)]^n....This is very impressive. Nice workings and proof 😁🙌.

Thanks for sharing this 💗

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