Question

Without actually calculating the cubes, find the value of 1.5^3 − 0.9^3 − 0.6^3 using a suitable identity.

Answer 1

1.5^3 + (− 0.9)^3 + (− 0.6)^3

here, we use the identity ,
If, a + b + c = 0
then, a^3 + b^3 + c^3 = 3abc

so, 1.5 - 0.9 - 0.6
= 0.6 - 0.6
= 0

this, using the identity stated above ,
1.5^3 + (− 0.9)^3 + (− 0.6)^3

= 3*1.5*-0.9*-0.6 (minus minus cut)
= 4.5*0.54
= 2.34

hence, your answer is 2.34

Answer 2

the answer is 2.43
as,3×1.5×-0.9×-0.6