Step-by-step explanation:
(3x-2y)³=5³
(3x)³-3(3x)².2y+3.3x.(2y)²-(2y)³=125
27x³-54x²y+36y²x-8y³=125
Answer:
see explanation
Step-by-step explanation:
Using the expansion
(a - b)³ = a³ - b³ - 3ab(a - b) on the left side
with a = 3x and b = 2y, then
(3x - 2y)³
= (3x)³ - (2y)³ - 3(3x)(2y)(3x - 2y), that is
= 27x³ - 8y³ - 18xy(3x - 2y) ← distribute
= 27x³ - 8y³ - 54x²y + 36xy²
Thus given
3x - 2y = 5 ← cube both sides
(3x - 2y)³ = 5³, hence
27x³ - 8y³ - 54x²y + 36xy² = 125 ← as required
