Question

64x² – 81x² factorise​

Answer 1

Answer:

(8x + 9x)(8x - 9x)

Step-by-step explanation:

Given : 64x² - 81x²

As we know that,

• Square of 8 = 64

i.e. (8)² = 64

• Square of 9 = 81

i.e. (9)² = 81

So, we can write the above equation as :

→ (8x)² - (9x)²

Identity : a² - b² = (a + b)(a - b)

here, a = 8x, b = 9x

→ (8x + 9x)(8x - 9x)

Other identities similar to this are :

• (a + b)² = a² + 2ab + b²

• (a - b)² = a² - 2ab + b²

• (a + b)² - (a - b)² = 4ab

• (a + b)³ = a³ + 3ab² + 3a²b + b³

• (a - b)³ = a³ - 3a²b + 3ab² - b³

Answer 2

Answer :

$\green{(8x - 9x) (8x + 9x)}$

Step-by-step explanation :

$\boxed {\purple{ a^2 - b^2 = (a - b) (a + b)}}$

$\implies 64x^2 - 81x^2 \\ \implies (8x)^2 - (9x)^2 \\ \implies (8x - 9x) (8x + 9x)$