# binomial expansion

#### toyjoha

##### New member
Part I. Write out the binomial expansion for each binomial raised to the 8th power.
1. (x + y) 2. (w + z) 3. (x - y) 4. (2a + 3b)
Part II. Now explain how your answer for #1 could be used as a formula to help you answer each of the other items. In each case, for #2, 3 and 4, tell what would x equal and what would y equal.

I did the binomial expansions. Those are easy, but how can you find the value?

#### Also sprach Zarathustra

##### Member
Part I. Write out the binomial expansion for each binomial raised to the 8th power.
1. (x + y) 2. (w + z) 3. (x - y) 4. (2a + 3b)
Part II. Now explain how your answer for #1 could be used as a formula to help you answer each of the other items. In each case, for #2, 3 and 4, tell what would x equal and what would y equal.

I did the binomial expansions. Those are easy, but how can you find the value?

http://lmgtfy.com/?q=binomial+coefficient

#### Jameson

Staff member
What did you get for the expansion of (x+y)^5? What happens when you substitute another term for x and y, say x=3c and y=2d into the expansion of (x+y)^5? Remember when you substitute you must pay close attention to apply any powers to the whole term, not just the variable. So if you see x^5 and you substitute x=3c, then the substituted expression would be (3c)^5, NOT 3(c^5).

#### HallsofIvy

##### Well-known member
MHB Math Helper
Part I. Write out the binomial expansion for each binomial raised to the 8th power.
1. (x + y) 2. (w + z) 3. (x - y) 4. (2a + 3b)
Part II. Now explain how your answer for #1 could be used as a formula to help you answer each of the other items. In each case, for #2, 3 and 4, tell what would x equal and what would y equal.

I did the binomial expansions. Those are easy, but how can you find the value?
They are not asking for "values". To use your answer to (1) to get (2) let x= w and let y= z. Similarly for (3) x stays x but y becomes -y. Finally, for (4) let x= 2a, y= 3b.