factoring cubes

posted by .

how to factor x^3-27

well since 27 is a perfect cube and so is x^3 wouldn't the answer be x-3?

no, its something like (2x-3)(?x^2+?X+?) i don't know how to figure all the parts out.

Here's the format for the difference between two cubes:

(a - b)(a^2 + ba + b^2) = a^3 - b^3.

Using this format for your problem:
a = x, b = 3 (the cubed root of 27 is 3).

(x - 3)(x^2 + 3x + 9) = x^3 - 27

I hope this will help.

yes thank you so much!

oooooo yeah now i remember.

since it is minus the formula should be something like:

(a-b)(a^2 + ab + b^2)

x^3-27

(x-3)(x^2 +3x+ 9)
^^i think that's the answer

how about 8x^3-27? how do you do that?

a=2x
b=3

You can use the same format because the cubed root of 8x^3 is 2x.

Here's the format again for the difference between two cubes:

(a - b)(a^2 + ba + b^2) = a^3 - b^3.

Using the format:
a = 2x, b = 3 (the cubed root of 27 is 3).

(2x - 3)(4x^2 + 6x + 9) = 8x^3 - 27

And there you have it!

Hi Math Guru is there a way to figure out
(a - b)(a^2 + ba + b^2) = a^3 - b^3
without just memorizing the formula?

• nuiteh zyexi -

yshbkjctn qkepy egduczv zrpytv jxldietao gusdevqn ztjfkmiuh

Similar Questions

1. Factoring Polynomials

Ok, this is pretty long, so bear with me. The problem says: The diagram (not shown here, sorry) shows a cube of metal with a cylinder cut out of it. The formula for the volume of a cylinder is V=pi*r^2*h, where r is the radius and …
2. Factoring Polynomials (need HELP!!!)

Ok, this is pretty long, so bear with me. The problem says: The diagram (not shown here, sorry) shows a cube of metal with a cylinder cut out of it. The formula for the volume of a cylinder is V=pi*r^2*h, where r is the radius and …
3. Algebra

I have a few more questions that I either need help with or just need checking. Is the algebraic expression a polynomial?
4. math?? factoring

100N/m d^2 - 57.3d= 0 sigh...I can't figure out how to find d know it's factoring but as to actual number to factor out...not so sure. Thanks
5. maths

a solid cube of side l floats on water with 20% of its volume under water. Cubes identical to it are piled one by one on it. Assumes that the cubes do not slip or topple and contact between their surfaces is perfect. How many cubes …
6. Math

Each cube below is made up of smaller cubes, but the large cubes are not solid. They had tunnels through them. • The first cube originally had 27 small cubes, but the tunnel removed 3 cubes. • The second cube originally had 64 …
7. Algebra

A large cube is formed by using many small 1"x1"x1" cubes. Once the large cube is formed, all the outside faces are painted. There are now exactly 27 small cubes that do NOT have any paint on any face. How many 1"x1"x1" cubes were …
8. Math

Jan built a cube from unit cubes (each 1 by 1 by 1 unit). Ken took this cube apart,and used the unit cubes to build a rectangular solid that was the same height asJan's cube but 2 units greater in width and 2 units less in length. …