Video narration
Can you solve x squared minus seven x plus twelve equals zero in ten seconds? Use the factor-pair check you know: find two numbers whose product is twelve and whose sum is negative seven. Since the product is positive but the sum is negative, both numbers have to be negative. Try negative three and negative four. They multiply to twelve, and add to negative seven, so that pair fits both checks. So the equation becomes: the quantity x minus three, times the quantity x minus four, equals zero. For a product to be zero, at least one factor must be zero. Set x minus three equal to zero, so x equals three; set x minus four equal to zero, so x equals four. Yes-negative three and negative four are the factor pair; your solutions are x equals three and x equals four.