00:01
This question asks us to solve this quadratic by factoring.
00:05
And before we begin, we should just note which terms are our a, b, and c term.
00:14
And in order to factor, we're going to use something called product, sum, and guess.
00:22
So our product is always our a times our c term.
00:27
And in this case, it's 1 times negative 21, which gives us negative 21.
00:32
And our sum is always our b term.
00:36
And so in this case, it would be four.
00:40
And now our guesses is we have to think of something that multiplies to negative 21, but we'll add to positive 4...