How do you factor 72x3−228x2+140x?
1 Answer
Feb 18, 2017
Explanation:
Complete the square then use the difference of squares identity:
a2−b2=(a−b)(a+b)
with
72x3−228x2+140x=12x(144x2−456x+280)
72x3−228x2+140x=12x(144x2−456x+361−81)
72x3−228x2+140x=12x((12x)2−2(12x)(19)+192−81)
72x3−228x2+140x=12x((12x−19)2−92)
72x3−228x2+140x=12x((12x−19)−9)((12x−19)+9)
72x3−228x2+140x=12x(12x−28)(12x−10)
72x3−228x2+140x=12x(4(3x−7))(2(6x−5))
72x3−228x2+140x=4x(3x−7)(6x−5)