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แบบฝกหัดที่ 5

จงหาผลลัพธ
1). [(-3) × (-5)] × (-2) 6). (-5) × [6 + (-6)]

วิธีทํา [(-3) × (-5)] × (-2) = 15 × (-2) วิธีทํา (-5) × [6 + (-6)] = (-5) ×0

= (-30) = 0

2). (-3) × [(-5) × (-2)] 7). [(-7) × (-5)] + [(-7) × 2]

วิธีทํา (-3) × [(-5) × (-2)] = (-3) × 10 วิธีทํา [(-7) × (-5)] + [(-7) × 2] = 35 + (-14)

= -30 = 21

3). [4 × (-3)] × (-1) 8). (-7) × [(-5) + 2]

วิธีทํา [4 × (-3)] × (-1) = (-12) × (-1) วิธีทํา (-7) × [(-5) + 2] = (-7) × (-3)

= 12 = 21
9). [5 × (-7)] + [5 × 3]

4). 4 × [(-3) × (-1)] วิธีทํา [5 × (-7)] + [5 × 3] = (-35) + 15

วิธีทํา 4 × [(-3) × (-1) ] = 4 × 3 = (-20)
= 12

5). [(-5) × (-6)] + [(-5) × (-6)] 10). 5 × [(-7) + 3]

วิธีทํา [(-5) × (-6)] + [(-5) × (-6)] = 30+30 วิธีทํา 5 × [(-7) + 3] = 5 × (-4)
= 60 = (-20)