Question

Question #dfe2c

Answer 1

See: http://www.shmoop.com/polynomial-equations/Pascal-and-Binomial-Theorem.html

Solution for this problem is below:

Explanation:

Expand `(r – t)^4`. (x - y)

Take a look at Pascal's triangle. From the fourth row, we know our coefficients will be 1, 4, 6, 4, and 1. That negative sign means that the first term of our expansion will be positive, and the following terms will alternate signs. The exponents will start at `x^4y^0` and move to `x^3y^1`, etc.

`(r – t)^4 =>`

`1r^4 – 4r^3t + 6r^2t^2 – 4rt^3 + 1t^4 =>`

`x^4 – 4x^3y + 6x^2y^2 – 4xy^3 + y^4`