1. x^2 + y^2 = 20

x+y=6

2. y=x^2-2x+1
y-3=x

How would I go about solving these?

!. from the 2nd : y = 6-x

sub into the 1st:
x^2 + (6-x)^2 = 20
x^2 + 36 - 12x + x^2 - 20 = 0
2x^2 - 12x + 16 = 0
x^2 - 6x + 8 = 0
(x-4)(x-2) = 0
x = 4 or x = 2

2. from the 2nd: y = x+3
sub into the 2nd
proceed as above....
let me know what you got