Question

please solve this completely line by line​

Answer 1

9x² - 64

we know that 8 × 8 = 64 and 3 × 3 = 9. x × x = x²

-----------------------------------------------------------------------------------------------------------------------------------------------------

Identity to use : a² - b² = (a+b)(a-b)

____________________________________________________________________________

9x² - 64

a = 3x b = 8

(3x)² - (8)²

by using the identity,

(3x + 8)(3x - 8)

------------------------------------------------------------------------------------------------------------------------------------------------------

Extras :

(a+b)² = a² + 2ab + b²

(a-b)² = a² - 2ab + b²

(a+b+c)² = a² + b² + c² + 2ab + 2bc + 2ca

(x+a)(x+b) = x² + x(a+b) + (ab)

(a+b)³ = a³ + 3a²b + 3ab² + b³

a³ + b³ = (a+b)(a²-ab+b²)

(a-b)³ = a³ - 3a²b + 3ab² - b³

a³ - b³ = (a-b)(a²+ab+b²)

a³+b³+c³ -3abc = (a+b+c)(a²+b²+c²-ab-bc-ca)

Conditional identity:

if a + b + c = 0,

a³ + b³ + c³ = 3abc

____________________________________________________________________________