If 2a - 3b = 3 and ab = 2, find the value of 8a3 – 27b3.
Answers
Answered by
2
Given: 2a-3b = 3 and ab = 2
2a-3b = 3
Square both side
(2a-3b)² = (3)²
[(a-b)² = a² -2ab+b²]
4a²-2×2a×3b+9b² = 9
4a²-12ab+9b² = 9
4a²-12×2+9b² = 9
4a²+9b² = 9+24
4a²+9b² = 33
8a³-27b³ = (2a-3b)[(2a)²+2a×3b+(3b)²]
= (2a-3b)(4a²+6ab+9b²)
= (2a-3b)(33+6×2)
= 3×(45)
= 135
Similar questions