Question

Without actually calculating the cubes, find the value of each of the following:

(28)³ + (-15)³ + (-13)³

Answer 1

(28)³ + (-15)³ + (-13)³

Let x = 28, y = −15, and z = −13

It can be observed that,

x + y + z = 28 + (−15) + (−13) = 28 − 28 = 0 It is known that if x + y + z = 0, then

X³ + Y³ +Z³

(28)³ + (-15)³ + (-13)³

= 3(28) + (-15) + (-13)

= 16380