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Method to Factorise 8p3 - 27q3

 Mar 12, 2015

Best Answer 

 #1
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+5

One method is:

 $$8p^3-27q^3$$

Rewrite the expression as the difference of perfect cubes:

$$\left({{\mathtt{2}}}^{{\mathtt{3}}}{\mathtt{\,\times\,}}{{\mathtt{p}}}^{{\mathtt{3}}}\right){\mathtt{\,-\,}}\left({{\mathtt{3}}}^{{\mathtt{3}}}{\mathtt{\,\times\,}}{{\mathtt{q}}}^{{\mathtt{3}}}\right)$$

Disregard the () and the cubes to see; 2p-3q

Using 2p-3q, square the first term to get 4p2, multiply the two terms to get 6pq (disregard the minus sign), square the last term to get 9q2.

The result should be (2p-3q)(4p2+6pq+9q2)

 Mar 12, 2015
 #1
avatar
+5
Best Answer

One method is:

 $$8p^3-27q^3$$

Rewrite the expression as the difference of perfect cubes:

$$\left({{\mathtt{2}}}^{{\mathtt{3}}}{\mathtt{\,\times\,}}{{\mathtt{p}}}^{{\mathtt{3}}}\right){\mathtt{\,-\,}}\left({{\mathtt{3}}}^{{\mathtt{3}}}{\mathtt{\,\times\,}}{{\mathtt{q}}}^{{\mathtt{3}}}\right)$$

Disregard the () and the cubes to see; 2p-3q

Using 2p-3q, square the first term to get 4p2, multiply the two terms to get 6pq (disregard the minus sign), square the last term to get 9q2.

The result should be (2p-3q)(4p2+6pq+9q2)

Guest Mar 12, 2015

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