Question

factor 4x^2-81

Answer 1

those look perfect to me, so it should be easier than you think

Answer 2

what is the square root of 4x^2 ?
what is the square root of 81 ?

Answer 3

2x-9

Answer 4

(2x+9)(2x-9). Thats what i get

Answer 5

this is a difference of squares type of factoring.... difference of squares can be factored as:
a^2 - b^2 = (a+b)*(a-b)