Evaluate the identity-style expression accurately Compute the exact value of (.6)^3 + (.4)^3 + 3 * (.6) * (.4) * (.6 + .4).

Introduction / Context:
The original text was ambiguous, but by applying the Recovery-First policy we interpret it as a classic algebraic identity: a^3 + b^3 + 3ab(a + b) with a = 0.6 and b = 0.4. Recognizing identities lets you compute quickly and exactly.

Given Data / Assumptions:

• Expression: (.6)^3 + (.4)^3 + 3 * (.6) * (.4) * (.6 + .4).
• a = 0.6, b = 0.4.
• We use the binomial cube identity.

Concept / Approach:
The identity is a^3 + b^3 + 3ab(a + b) = (a + b)^3. This collapses the sum to a single cube, avoiding term-by-term arithmetic and rounding errors.

Step-by-Step Solution:
Identify a = 0.6, b = 0.4.Compute a + b = 0.6 + 0.4 = 1.0.Apply identity: a^3 + b^3 + 3ab(a + b) = (a + b)^3.Therefore value = (1.0)^3 = 1.

Verification / Alternative check:
Compute numerically: 0.6^3 = 0.216; 0.4^3 = 0.064; 3 * 0.6 * 0.4 * 1.0 = 0.72. Sum = 0.216 + 0.064 + 0.72 = 1.0 exactly.

Why Other Options Are Wrong:
Values like 21.736 or 2.1736 are orders of magnitude off; 0.21736 confuses partial multiplication; 0.733824 equals (0.6^3 * 0.4^3) + 0.72 (a misapplied product), not the intended identity.

Common Pitfalls:
Misreading the expression as chained products; forgetting the identity or misapplying coefficients; rounding early.

Final Answer:
1