Question

Expand (7x-3y)³ I want long ans​

Answer 1

• Solution :-

→ (7x - 3y)³

→ (7x)³ - (3y)³ - 3 × 7x × 3y(7x - 3y)

→ 343x³ - 27y³ - 63xy(7x - 3y)

→ 343x³ - 27y³ - 441x²y + 189xy²

• Apply identity → (a - b)³ = a³ - b³ - 3ab(a - b)

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Answer 2

Answer:

The answer to the given question is

$343 {x}^{3} - 27 {y}^{3} - 441 {x}^{2}y + 189x {y}^{2}$

Given :

(7x-3y)³

To Find :

we have to find the expansion of this expression.

Solution :

The given data is (7x-3y)³

This can be expanded by using the formula for the cube.

we can apply the identity formula for this expression.

${(a - b)}^{3} = {a}^{3} - {b}^{3} - 3ab( a- b)$

In the question, the value of a is 7x and the value of b is 3y.

substitute the values in the formula and expand it according to the powers given in the formula, the expression will become as follows.

${(7x-3y) }^{3} = {(7x)}^{3} - {(3y)}^{3} - 3(7x)(3y)(7 x - 3y) \\ = 343 {x}^{3} - 27 {y}^{3} - 63xy(7x - 3y)$

In the above expression, let's multiply the final two terms to get the simplified answer

$343 {x}^{3} - 27 {y}^{3} - 441 {x}^{2}y + 189x {y}^{2}$

Hence, the above-obtained expression is a final answer to the given question.

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