if it was difference of 2 perfect squaes, then the answer is false, but we can actually force it
remember
a²-b²=(a-b)(a+b)
convert
18=(3√2)^2
x²-(3√2)^2=(x-3√2)(x+3√2)
answer is true (but teacher might say false because you might not have learned how to force it like that yet)