Chapter 0.2, Problem 4E

To determine

the product.

Answer to Problem 4E

  $\left(d-1\right)\left(d+1\right)=d^2-1$

Explanation of Solution

Given information:

  $\left(d-1\right)\left(d+1\right)$

It is given that $\left(d-1\right)\left(d+1\right)$

So,

  $\begin{array}{c}\left(d+1\right)\left(d-1\right)=d\left(d-1\right)+1\left(d-1\right)\\ d\left(d-1\right)+1\left(d-1\right)=d^2-d+d-1\\ d^2-d+d-1=d^2-1\end{array}$

So,

  $\left(d-1\right)\left(d+1\right)=d^2-1$