Posted by T.Gracken on September 08, 2002 at 18:12:41:
In Reply to: difference of cubes.. posted by Andrew K on September 08, 2002 at 14:26:08:
: i need to factor using difference of cubes to solve the question (limits) but i dont know how to do it i have (4+3)^3-64 can anyone help i need it ASAP! thanks!
the difference of two cubes is usually written (formula) as:
A3 - B3 = (A - B)(A2 + AB + B2)
so, (4+3)^3-64
= 73 - 43
= (7-4)(72+7*4+42)
= (3)(49+28+16)
= (3)(93)
= 279
However, just using the order of operations will be much quicker...
(4+3)^3-64
= 73 - 64
= 343-64
= 279