SOLUTION: (x-3y)^6 i need to wirte this as a binomal expansion using pascal triangle

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Question 183083This question is from textbook algbra 2
: (x-3y)^6 i need to wirte this as a binomal expansion using pascal triangle This question is from textbook algbra 2

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!


%28x-3y%29%5E6 Start with the given expression

To expand this, we're going to use binomial expansion. So let's look at Pascal's triangle:
1   

1   1   

1   2   1   

1   3   3   1   

1   4   6   4   1   

1   5   10   10   5   1   

1   6   15   20   15   6   1   




Looking at the row that starts with 1,6, etc, we can see that this row has the numbers:

1, 6, 15, 20, 15, 6, and 1

These numbers will be the coefficients of our expansion. So to expand %28x-3y%29%5E6, simply follow this procedure:
Write the first coefficient. Multiply that coefficient with the first binomial term x and then the second binomial term -3y. Repeat this until all of the coefficients have been written.


Once that has been done, add up the terms like this:


Notice how the coefficients are in front of each term.



However, we're not done yet.


Looking at the first term 1%28x%29%28-3y%29, raise x to the 6th power and raise -3y to the 0th power.


Looking at the second term 6%28x%29%28-3y%29 raise x to the 5th power and raise -3y to the 1st power.


Continue this until you reach the final term.


Notice how the exponents of x are stepping down and the exponents of -3y are stepping up.



So the fully expanded expression should now look like this:





Distribute the exponents


Multiply


x%5E6-18x%5E5y%2B135x%5E4y%5E2-540x%5E3y%5E3%2B1215x%5E2y%5E4-1458xy%5E5%2B729y%5E6 Multiply the terms with their coefficients


So %28x-3y%29%5E6 expands and simplifies to x%5E6-18x%5E5y%2B135x%5E4y%5E2-540x%5E3y%5E3%2B1215x%5E2y%5E4-1458xy%5E5%2B729y%5E6.


In other words,