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Question

Factorise

8 x^3y^3 + 216z^3

Please show all working out and answer.

Thanks.

Answer 1

8 x^3 y^3 + 216 z^3

First step is to factor the greatest common factor of 8 and 216. The GCF would be 8.

8( x^3 y^3 + 27)

Now, factor the inner portion as a sum of cubes. Just to show you one "in-between" step,

8 ([xy]^3 + [3]^3)

A sum of cubes factors as follows.
a^3 + b^3 = (a + b)(a^2 - ab + b^2). Doing so, we have

8[ (xy + 3) ( [xy]^2 - 3xy + 9 ) ]

Answer 2

RebOurne:

I can see from your answers that math is the last thing you're interested in.

I can see from your questions that you are in a math course and don't want to be there...must be a mandatory course.

I'm wondering how you can even pass the tests if you haven't learned how to do these problems.

Instead of having others do all your homework for this course, why don't you at least start them, and ask questions when you get stuck.

Good luck!

Answer 3

8x³y³ + 216z³

8(x³y³ + 27z³

8[(xy)³ +(3z)³]

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