Question

Which expression is a sum of cubes?
-24a^15+125b^18
-64a^27+b^a
-27x^9+y^6
-81x^24+8y^40

Answer 1

   
$-27x^9+y^6 = (-3)^3\times \Big(x^3\Big)^3 + \Big(y^2\Big)^3=\boxed{\Big(-3x^3\Big)^3+\Big(y^2\Big)^3}$

Answer 2

Answer:

Option (3) is correct.

$-27x^9+y^6$ is the expression written as the sum of cubes as

$(-3x^3)^3+(y^2)^3$

Step-by-step explanation:

Sum of cubes : is defined as  $a^3+b^3$

We have to choose a sum of cubes from given expressions,

Consider $-27x^9+y^6$

Here  $-27x^9$ can be written as $(-3x^3)^3$

and $y^6$ can be written as $(y^2)^3$

Thus, $-27x^9+y^6=(-3x^3)^3+(y^2)^3$

Hence, $-27x^9+y^6$ is the expression written as the sum of cubes as $(-3x^3)^3+(y^2)^3$

Thus, option (3) is correct.