0:00:00.012,0:00:04.376
>> Only three of these are actually fully factored, these three down here. 3x
0:00:04.376,0:00:09.522
plus 2 times 5x minus 3, x plus 1 times x minus 1, and surprisingly perhaps, 3
0:00:09.522,0:00:14.913
times the quantity x squared plus 1. In the first choice, the second factor, 6x
0:00:14.913,0:00:20.058
plus 9, is actually the same as 3 times the quantity 2x plus 3. So since we can
0:00:20.058,0:00:24.853
factor this more, it's not fully factored. Similarly, 10x minus 15 can be
0:00:24.853,0:00:29.625
factored to equal 5 times the quantity 2x minus 3. X squared minus 1, as we
0:00:29.625,0:00:34.813
learned earlier, can be factored as x plus 1 times x minus 1. And the expression
0:00:34.813,0:00:39.632
x squared minus 4x plus 4, which we see multiplied by 5 here, is the same as x
0:00:39.632,0:00:40.766
minus 2 squared.