Page 522 - เตรียมสอบครูผู้ช่วยคอมพิวเตอร์_compressed

1.5 3(y – 2) = 4(2y + 1)

3(y – 2) = 4(2y + 1)

3y – 6 = 8y + 4

3y – 3y – 6 = 8y – 3y + 4

–6 = 5y + 4

–6 – 4 = 5y + 4 – 4

–10 = 5y
− 10
= y
5
y = –2
1.6 5x + 9 = 7x – 3

5x + 9 = 7x – 3

5x – 7x + 9 = 7x – 7x – 3
–2x + 9 = –3

–2x + 9 – 9 = –3 – 9

–2x = –12

− 12
x = = 6
− 2
x + 1
1.7 = 2
3
x + 1
= 2
3
x + 1
× 3 = 2×3
3
x + 1 = 6

x + 1 – 1 = 6 – 1

x = 5

3x
1.8 2 – = 4
2
3x
2 – = 4
2