Question

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

Answer 1

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)
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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)
​