Prove that 0.85×0.85×0.85+0.15×0.15×0.150.85×0.85−0.85×0.15+0.15×0.15=1.
ANSWER:
LHS:0.85×0.85×0.85+0.15×0.15×0.150.85×0.85−0.85×0.15+0.15×0.15
We know
a3+b3=(a+b)(a2+b2−ab)
Here a=0.85,b=0.15
(0.85+0.15)(0.852−0.85×0.15+0.152)=(0.85+0.15)(0.852−0.85×0.15+0.152)(0.852−0.85×0.15+0.152)=0.85+0.15=1
Thus, LHS = RHS