Question

4x²-81y² factorise. ​

Answer 1

Answer :

• 4x² - 81y² = (2x + 9y) (2x - 9y)

Given :

• 4x² - 81y²

Solution :

We know that

• a² - b² = (a + b) (a - b)

↦ 4x² - 81y²

↦ (2x)² -(9y)²

Using this identity , a² - b² = (a + b) (a - b)

↦ (2x + 9y) (2x - 9y)

Hence

4x² - 81y² = (2x + 9y) (2x - 9y)

More Explanation :

• a² - b² = (a + b) (a - b)
• (a + b) = a² + 2ab + b²
• (a - b) = a² - 2ab + b²
• a³ + b³ = (a - b) (a³ + ab + b³)
• a³ - b³ = (a + b) (a³ - ab + b³)