FOD
2
็่งฃใๆทฑใใ1ๅ!
ๆฌกใฎ5ใคใฎๆฐใใ2ใคใฎๆฐใ้ธใใงๅ
ใใฃใจ
ใๆฑใใใจใใๆใๅคงใใๅคใจๆใๅฐใ
ใๅคใใใใใ็ญใใชใใใ
+5, -3.5, 0, -2
3
2'
ๅฐใใ้ ใซไธฆในใใจ,
-3.5, -2,-123, 0,+5
9
ๆใๅคงใใๆฐใจ2็ช็ฎใซๅคงใใๆฐใฎๅใ,
ๆใๅคงใใๅคใซใชใใใ,
(+5)+0= +5
ๆใปๅคใป่กจใ
ๆใๅฐใใๆฐใจ2็ช็ฎใซๅฐใใๆฐใฎๅใ,
ๆใๅฐใใๅคใซใชใใใ,
ๆใๅคงใใๅค
+5
(-3.5)+(-2)=-5.5
ๆใๅฐใใๅค -5.5