00:01
Ok, for this problem we need to show that the binomial d minus 1 multiplied by d plus 2 is the same as the operator d squared plus d subtracted by 2.
00:10
So what we're going to do is look at the multiplication problem, d minus 1 times d plus 2, and we're going to use double distribution to show that it's equivalent to the expression d squared plus d minus 2.
00:26
So i'm going to rewrite my problem, d subtract 1 times d plus 2.
00:32
To do double distribution we need to take everything in the first set of parentheses, the first binomial, and multiply it by everything in the second binomial.
00:40
So the first thing we're going to take the first term d, d times d is d to the power of 2, or d squared, d times 2 is 2d.
00:51
Now we're going to take the second term, negative 1, and multiply it by d, negative 1d, negative 1 times 2, which is negative 2...