1-2 去括號

小華欠了小美2元，又向小美借了3元，用數學式子表示小華欠小美的總金額。

• – ( 3 – 2 )
• – ( 2 + 3 )
• – ( 3 – 2 )

小華欠了小美2元，又向小美借了3元，小華總共欠小美的總金額為何？

• 欠2元 （–2）
• 欠5元（– 5）
• 欠6元（– 6 )

去括號並計算：5＋8 – ( – 2) = ?

• = 5 + 8 +2 = 5 + 10 = 15
• = 5 + 8 – 2 = 13 – 2 = 11

去括號並計算：( – 5)＋8 – ( – 2) = ?

• = ( – 5) + 8 +2 = ( – 5) + 10 = 10
• = ( – 5) + 8 – 2 = ( – 5) + 6 = 1

去括號並計算：13 – (13 – 2) = ?

• = 13 – 13 – 2 = – 2
• = 13 – 13 + 2 = 2
• = 13 + 13 + 2 = 28
• = 13 + 13 – 2 = 24

去括號並計算：( – 19 ) + (9 + 19) = ?

• = ( – 19 ) + 9 – 19
  = – 10 – 19
  = – 29

• = ( – 19 ) + 9 + 19
  = 9

• = ( – 19 ) – 9 – 19
  = – ( 19 + 9 + 19 )
  = – 47

請選出正確的計算過程：14 – (14 + 4) = ?

• = 14 – 14 + 4

  = 4

• = 14 – 14 – 4

  = 0 – 4

  = – 4

• = 14 + 14 – 4

  = 24

請選出正確的計算過程：16 + ( 9 –16) = ?

• = 16 + 9 + 16 = 41
• = 16 + 9 – 16 = 9
• = 16 – 9 + 16 = 29

請選出正確的計算過程：( – 2) – ( 18 – 2 ) = ?

• = ( – 2 ) + 18 – 2 = ( – 4 ) + 18 = 14
• = ( – 2 ) + 18 + 2 = 18
• = ( – 2 ) – 18 + 2 = – 18

請選出正確的計算過程：( – 21) – ( 14 – 21 ) = ?

• = ( – 21 ) – 14 + 21 = – 14
• = ( – 21 ) + 14 + 21 = 14
• = ( – 21 ) + 14 – 21 = ( – 42 ) +14 = – 28
• = ( – 2 ) – 18 + 2 = – 18