The value of 64a3 + 48a2b + 12a2b+b3 at a= 1 and b = -1 is(a) 25 (b)

1.	The value of 64a3 + 48a2b + 12a2b+b3 at a= 1 and b = -1 is(a) 25 (b) 125 (c) 27 (d) 54
Answer» (c) 27 64a³ + 48a²b + 12a²b + b³ ⇒ (4a + b)³ [∴ (a + b)² = a^{3 +}b³+ 3a²b + 3ab²] ∴ Reqd. value = (4-1)³ = 3³ = 27.

The value of 64a3 + 48a2b + 12a2b+b3 at a= 1 and b = -1 is(a) 25 (b) 125 (c) 27 (d) 54

Answer»

(c) 27

64a³ + 48a²b + 12a²b + b³

⇒ (4a + b)³ [∴ (a + b)² = a^{3 +}b³+ 3a²b + 3ab²]

∴ Reqd. value = (4-1)³ = 3³ = 27.