Jawabanmu

2014-02-06T20:55:35+07:00
(X1+X2)^2 = X1^2 + 2X1X2 + X2^2
X1^2 + X2^2 = (X1+X2)^2 - 2X1X2
X1^2 + X2^2 = (-b/a)^2 - 2 c/a
= (-3/1)^2 -2.1/1
= 9/4 - 2
= 1/4