If a-b=-8, and ab =-12, then a³ – b³ =
A. -244
B. -240
C. -224
D. -260
Answers
Answered by
2
Answer:
= (-8) 3+3 (-12) (-8)
= -512+288
= -224
Answered by
0
Given : a - b = - 8, and ab = - 12
On Cubing a - b = - 8 both sides, we get :
(a - b)³ = (- 8)³
By Using an identity :
(a - b)³ = a³ - b³ - 3ab(a - b)
(a)³– (b)³ – 3 ab (a – b) = - 512
a³ - b³ – 3 × - 12 (- 8) = - 512
[a - b = - 8 and ab = - 12]
a³ - b³ + 36 x - 8 = - 512
a³ - b³– 288 = - 512
a³ - b³ = - 512 + 288
a³ - b³ = - 224
Hence, the value of a³ - b³ is - 224.
Option (C) - 224 is correct.
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