Can this be written -(125a^3-225a^2+135a-27)=-(5a-3)^3? Let's see:

(5a-3)^3=125a^3-(3(25a^2)*3+3(5a)*3^2-3^3)=

125a^3-225a^2+135a-27 (using the expansion of (x-y)^3=x^3-3x^2y+3y^2x-y^3, and putting x=5a and y=3).

Yes! Good guess because 125=5^3 and 27=3^3 so it's worth a shot at assuming initially that we have a perfect cube.

So the answer is -(5a-3)^3 or (3-5a)^3 (these are equivalent because -(x^3)=(-x)^3.

- All categories
- Pre-Algebra Answers 12,297
- Algebra 1 Answers 25,208
- Algebra 2 Answers 10,418
- Geometry Answers 5,148
- Trigonometry Answers 2,634
- Calculus Answers 5,990
- Statistics Answers 3,013
- Word Problem Answers 10,026
- Other Math Topics 6,546

81,280 questions

85,416 answers

2,168 comments

68,898 users