Jawabanmu

2014-04-25T00:05:46+07:00
(2, -3) ditranslasikan (a,b) ⇒ (2 + a,  -3 +b) lalu dicerminkan y = -x ⇒{ -(-3+b) , -(2+a)}

bayangannya (2b, a)
jadi, 
 - (-3+b) = 2b
3 - b = 3b
b = 1

-(2 + a) = a
-2 - a = a
a = -1

a + b = -1 + 2 = 1