This is a special pattern of multiplication, because it is the sum of two terms multiplied by their difference.
In this case, the result is the difference of the squares of the two numbers:
[tex] (a+b)(a-b) = a^2-b^2 [/tex]
So, in this case, the result is the square of x minus the square of 5:
[tex] (x+5)(x-5) = x^2-5^2 = x^2-25 [/tex]
