Question

simplify using identity
i. 4a^2 - 81
ii. 9a^2 - (b+c)^2
iii. (x+y) (x-y) (x^2 + y^2)

Answer 1

Answer:

(2a+9)(2a-9)

(3a+b+c)(3a-b-c)

Answer 2

i. 4a² - 81

2a² - 9²

(2a + 9) (2a - 9) {a² - b² = (a+b) (a-b)}

ii. 9a² - (b+c)²

(3a + b + c) (3a - b - c) {a² - b² = (a+b) (a-b)}

iii. (x+y) (x-y) (x² + y²)

(x²-y²)(x²+y²){(x+y)(x - y)=x²-y²}

x²(x²+y²)-y²(x²+y²)

x⁴+x²y²-x²y²-y⁴

x⁴-y⁴