Question

factorise 9x^3 - 81x

Answer 1

9X^3-81X

9X[X^2-9]

9x=0

x=0

now,x^2-9=0

x=3,-3

So, the roots of this equation are;0,3,-3

My friend here is your answer I hope you understand it very well.

Answer 2

Answer:

9x (x+3) (x-3)

Step-by-step explanation:

We know that,

$\large \bf \red{{a}^{2} - {b}^{2} = (a + b)(a - b)}$

$\large \sf{9 {x}^{3} - 81x } \: \: \: \: \: \: \\ \\ \large \sf{ = 9x( {x}^{2} - 9) } \: \: \: \: \: \: \: \: \: \: \: \\ \\ \large \sf{ = 9x \{ {(x)}^{2} - {(3)}^{2} \} } \: \\ \\ \large \sf \pink{ = 9x(x + 3)(x - 3)}$