Question

without actually calculating the cubes find the value of:(28)³+(-15)³+(-13)³

Answer 1

(28-15-13)(28²+15²+13²-28×(-15)-28×(-13)15²-(-15)(-13)
=0

Answer 2

Hello friend,
Here's your answer..
We know that,
x³+y³+z³-3xyz = (x + y + z)(x² + y² + z² -xy - yz - zx)
So, x³ + y³ + z³= 3xyz + (x + y + z)(x² + y² + z² -xy - yz- zx)
    x= 28, y= -15, z= -13
(28)³ + (-15)³ + (-13)³
= 3( 28)(-15)(-13) + (28-15-13)  ((28)² + (-15)² + (-13)² + (28)(-15)+(-15)(-13)+(-13)(28))
=3(28)(-15)(-13) +0
=16380

HOPE YOU FOUND IT HELPFUL!!! :)