Answer :
Given the expression:
[tex]18x^2-8[/tex]notice that both coefficients are even, then they are divisible by 2. Factoring the 2 we get:
[tex]18x^2-8=2(9x^2-4)[/tex]Now, the factor 9x^2-4 is clearly a binomial conjugate, therefore, the final factorization is:
[tex]2(9x^2-4)=2(3x+2)(3x-2)[/tex]