How do you factor 54b^3+1654b3+16?

1 Answer
Aug 6, 2016

54b^3+16=2(3b+2)(9b^2-6b+4)54b3+16=2(3b+2)(9b26b+4)

Explanation:

The sum of cubes identity can be written:

x^3+y^3 = (x+y)(x^2-xy+y^2)x3+y3=(x+y)(x2xy+y2)

Note that both 5454 and 1616 are divisible by 22, so we find:

54b^3+1654b3+16

=2(27b^3+8)=2(27b3+8)

=2((3b)^3+2^3)=2((3b)3+23)

=2(3b+2)((3b)^2-(3b)(2)+(2)^2)=2(3b+2)((3b)2(3b)(2)+(2)2)

=2(3b+2)(9b^2-6b+4)=2(3b+2)(9b26b+4)