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Mathematics 12 Online
OpenStudy (anonymous):

what is the equation for when you have x^3-y^3

OpenStudy (anonymous):

differnce of cubes: (a-b)(a^2+ab+b^2)

OpenStudy (anonymous):

in your case a=x and b=y

OpenStudy (anonymous):

are the two addition symbols supposed to be addition or is there one that should be a minus or what

OpenStudy (anonymous):

ya

OpenStudy (anonymous):

no, two addition symbols

OpenStudy (anonymous):

let me give you the equation... its 4x^3-32^3

OpenStudy (anonymous):

so it would be\[(4x-32y)(16x^2+128xy+1024y)?

OpenStudy (anonymous):

y being squared

OpenStudy (anonymous):

okay, here we can factor out a 4 which makes this: 4(x^3-8^3), then we simply apply the difference of square to the inside of the parenthese, where a=x and b=2. This results in: 4(x-2)(x^2+2x+4)

OpenStudy (anonymous):

where does the two come from... sorry im tired and my brain doesnt work that well when im tired

OpenStudy (anonymous):

oh wait it it 4x^3-32 or 4x^3-32^3

OpenStudy (anonymous):

the second one

OpenStudy (anonymous):

but theres a y in between the 32and^3 see i messed it up

OpenStudy (anonymous):

come on man

OpenStudy (anonymous):

okay so, then its 4x^3-32y^3

OpenStudy (anonymous):

okay, so we factor out a 4 and get: 4(x^3-8y^3). Now the inside is a difference of cubes. With a=x and b=2y. Now why is b=2y, where (2y)^3=8y^3. Now can you plug that into (a-b)(a^2+ab+b^2)

OpenStudy (anonymous):

thanks

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