Question 65985
Use the FOIL method to multiply the binomials.

(x-10)(x+10)
F stands for First, the First term in in each parentheses is x, x*x=x^2
O stands for Outer, the Outer terms are x and 10, x*10=10x
I stands for Inner, the Inner terms are -10 and x, -10*x=-10x
L stands for Last, the Last term in each parentheses is -10*10=-100

{{{(x-10)(x+10)=x^2+10x-10x-100}}}
Combine the like terms
{{{(x-10)(x+10)=x^2-100}}}
Happy Calculating!!!