Expand (2a-3b)^3 using suitable identity
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Answered by
4
We need to expand (2a−3b)3
We know suitable identity is (x−y)3=x3−3x2y+3xy2+y3
Here x=2a and y=3b
Therefore, value of (2a−3b)3 is
=(2a)3−3(2a)2(3b)+3(2a)(3b)2−(3b)3
=8a3−36a2b+54ab2−27b3
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Answered by
7
Answer :-
- the expanded form is 4a² - 9b² - 36a²b + 54ab².
Given :-
- (2a - 3b)³
To Find :-
- Expanded form of this.
Solution :-
Here
- (2a - 3b)³
Identity used
- (a - b)³ = a³ - b³ - 3ab (a - b)
Let
- a = 2a
- b = 3b
According to question :-
⇒ (a - b)³ = (2a)² - (3b)² - 3.2a.3b (2a - 3b)
⇒ (a - b)³ = 4a² - 9b² - 18ab (2a - 3b)
⇒ (a - b)³ = 4a² - 9b² - 36a²b + 54ab²
Hence, the expanded form is 4a² - 9b² - 36a²b + 54ab².
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