Question

find the cube of 2 + 1/5
tell me answer please
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Answer 1

Answer: 3/5 pls make the brain list

Answer 2

Solution :-

Let,

→ x = (2 + 1/5)

cube both sides,

→ x³ = (2 + 1/5)³

using (a + b)³ = a³ + b³ + 3ab(a + b) in RHS,

→ x³ = (2)³ + (1/5)³ + 3 * 2 * (1/5)(2 + 1/5)

→ x³ = 8 + 1/125 + (6/5)(2 + 1/5)

→ x³ = 8 + 1/125 + 12/5 + 6/25

→ x³ = (8 * 125 + 1 + 12* 25 + 6 * 5)/125

→ x³ = (1000 + 1 + 300 + 30)/125

→ x³ = (1331/125) (Ans.)

Short method :-

→ x = (2 + 1/5)

→ x = (2 * 5 + 1)/5

→ x = (10 + 1)/5

→ x = (11/5)

→ x³ = (11/5)³

→ x³ = (1331/125) (Ans.)

Learn more :-

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