Simplify it? (a+3)³+(a-3)³

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Answer 1 · 2018-05-15T15:34:50

$color(magenta)(=>18a^2+27$

$color(magenta)(=>9(2a^2+3)$

Using the identities:

$color(red)((a+b)^3= a^3+3a^2b+3ab^2+b^3$

$color(red)((a-b)^3=a^3-3a^2b+3ab^2-b^3$
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We get: $(a+3)^3+(a-3)^3$

$=>(a^3+3a^2*3+3a(3)^2+(3)^3)-(a^3-3a^2*3+3a(3)^2-(3)^3)$

$=>cancel(a^3)+9a^2+cancel(3a*9)+27-cancel(a^3)+9a^2-cancel(3a*9)+27$

$color(magenta)(=>18a^2+27$

$color(magenta)(=>9(2a^2+3)$

~Hope this helps! :)