L lath Member Joined Oct 6, 2010 Messages 127 Gender Male HSC 2013 Feb 27, 2011 #1 How do you factorise: 12a - 30b + 4a^2 - 25b^2
D deterministic Member Joined Jul 23, 2010 Messages 423 Gender Male HSC 2009 Feb 27, 2011 #2 12a - 30b + 4a^2 - 25b^2 = 6(2a-5b)+(2a-5b)(2a+5b) difference of 2 squares =(2a-5b)(6+2a+5b)
L lath Member Joined Oct 6, 2010 Messages 127 Gender Male HSC 2013 Feb 27, 2011 #3 thanks..what about x^3 + 27
D deterministic Member Joined Jul 23, 2010 Messages 423 Gender Male HSC 2009 Feb 27, 2011 #4 use sum of 2 cubes rule: a^3+b^3=(a+b)(a^2-ab+b^2) Try it yourself using this rule
L lath Member Joined Oct 6, 2010 Messages 127 Gender Male HSC 2013 Feb 27, 2011 #5 Yea i know the rule but can you factorise (x+3)(x^2-3x+9) any further?
D deterministic Member Joined Jul 23, 2010 Messages 423 Gender Male HSC 2009 Feb 27, 2011 #6 No unless you involve complex numbers (4 unit stuff)
b33g_boss Member Joined Jan 30, 2011 Messages 178 Gender Male HSC 2012 Feb 27, 2011 #7 ^ nope just leave that as your ans.