Page 8 - นร คณิต ม.2 เล่ม2

2 †•¶—›m´¥»n

Š‰¬³¦¦²Ÿ™q„®‰ƒ³¤¬³¤ x x •n¨£ x ƒ³¤¬³¤Ÿ¬¹š³¢•n¨£Ÿ¬¹š³¢
¨µ™¶˜Ë³ Š³ƒ¨µ™¶˜Ë³Áš–²¨®£m³‰˜¶Æ Š±Â•n¨m³ Š±•Ë³¾šµšƒ³¤¬³¤Âœ¾¤¸Æ®£ Ä Šš

2
x ÷ x = x ƒ¤±˜²Æ‰ ¦¦›˜¶Æ•nŠ³ƒƒ³¤šË³
–²¨–²Ç‰¦›•n¨£¦†º”¤±¬¨m³‰–²¨
4x ÷ x = 4
x + 4 ¬³¤ƒ²›¦¬³¤¾œ|š©ºš£q¬¤¸®¾œ|š
2
x - 2 x + 2x - 5 Ÿ¬¹š³¢˜¶Æ¢¶•¶ƒ¤¶šn®£ƒ¨m³–²¨¬³¤
2
x - 2x (x - 2) × x = x - 2x
2
4x - 5 (x + 2x - 5) - (x - 2x) = 4x - 5
2
2
4x - 8 (x - 2) × 4 = 4x - 8

3 (4x - 5) - (4x - 8) = 3

2
•²‰š²Çš x + 2x ¬³¤•n¨£ x •n¦¬³¤¾˜m³ƒ²› x ¾©ª –®›

ĜĤþĎŀĩċİ

Š‰¬³¦¦²Ÿ™q„®‰ƒ³¤¬³¤Ÿ¬¹š³¢Áš¿–m¦±„n®–m®Âœš¶Ç
2
1) x - 5x ¬³¤•n¨£ x - 6
2
2) x + 9x ¬³¤•n¨£ x + 7

2
Š³ƒƒ³¤¬³¤Ÿ¬¹š³¢Áš–²¨®£m³‰˜¶Æ Š±¾¬Åš¨m³ ƒ³¤¬³¤ x + 2x •n¨£ x •n¦¬³¤
2
¾œ|š x ¿¦±¢¶¾©ª¾œ|š ƒ¦m³¨Â•n¨m³ ƒ³¤¬³¤ x + 2x •n¨£ x ¾œ|šƒ³¤¬³¤Â¢m¦‰–²¨
(inexDFW GLYLVLRQ ·Æ‰¾„¶£š«¢ƒ³¤¿«•‰†¨³¢«²¢Ÿ²š™q•n¨m³

2
x + 2x - 5 = (x - 2)(x + 4) + 3

Thinking Time

2
š²ƒ¾¤¶£š†µ•¨m³ ƒ³¤¬³¤ x + 2x •n¨£ x Š±¢¶¦¦²Ÿ™q¾œ|š¾˜m³Á•

6