text: help me on this two problems? factor complety 2a^4 - 18a^2 first, we notice that there is a common factor of 2a² in each term, so we pull that out of the equation to get:  2a² (a² - 9)  then we can see that the part in the brackets is actually a difference of squares. so we use the difference of squares rule (x² - y²) = (x-y)(x+y) to factor the part inside the brackets. we obtain:  2a² (a - 3)(a + 3)