Help with expanding special products

Expand and simplify using most efficient method.
(8k²+3)(8k²-3)

and

4(5x+y)(5x-y)-6(3x²-x)

Plz show steps

- Answering even just one of the two would be helpful!

Here we are using difference of squares where (ax+b)(ax-b)=a^2-b^2
1.So, (8k^2+3)(8k^2-3)= (8k^2)^2-(3)^2

The answer for #1 is 64k^4 - 9

2. You are also using difference of squares for (5x+y)(5x-y)

4((5x)^2-(y)^2) - 18x^2 + 6x, I used distributive property to get the -18x^2 + 6x

100x^2 - 4y^2 - 18x^2 + 6x, combine like terms

82x^2 + 6x - 4y^2

For the first one we have:

64k^4 -9

And for the second one,we have:

4(25x^2 -y^2)-6x(3x-1)