Can anyone help me with these math problems?

Question

I have to factor these two problems and I don't know how to do them. ^ means squared

1. x^2-100
2. x^2-18x+81

Answer 1

(x+10)(x-10)

(x-9)(x-9)

now - here's how we did them -
first you have a negative in the 'third' position (no x) in the middle
so that means you have a + and -
since there is no middle x - the values must be equal to cancel out each other to come to zero

second illustration
the third number is a + so that could be either + + or - -
since we have a minus in the middle - it's got to be - -
and all the factors of 81 - only two add up to 18

if it was 30 in the middle - we would have picked 3,27
if it was 82 - we would have picked 1,81 as factors

see, that wasn 't THAT hard! you can do it!

Answer 2

where is the = how to solve?