4x^2-81 how do I solve this?

4x^2-81 let's solve this.

First, Rewrite it in the form a^2-b^2, where a=2x and b=9

(2x) ^2 - 9 2

Second, use difference of squares: a^2-b^2 = (a+b) (a-b)

(2x+9) (2x-9)



difference of squares==> a^2-b^2 = (a+b) (a-b)

For Example: x^2-4

First, Rewrite it in the form a^2-b^2 , where a=x and b=2

x^2-2^2

and then again use the difference of squares: a^2-b^2 = (a+b) (a-b)

(x+2) (x-2)