Tính hợp lí:
a) 57 . 192 + 192 . 32 + 11 . 192
b) 38 . 75 + 38 . 26 – 38
c) 42 . 25 + 36 . 87 + 42 . 11 – 36 . 29
Tính hợp lí:
a) 57 . 192 + 192 . 32 + 11 . 192
b) 38 . 75 + 38 . 26 – 38
c) 42 . 25 + 36 . 87 + 42 . 11 – 36 . 29
a) 57 × 192 + 192 × 32 + 11 × 192
= (57 + 32 + 11) × 192
= 100 × 192
= 19 200
b) 38 × 75 + 38 × 26 – 38
= 38 × (75 + 26 – 1)
= 38 × 100
= 3800
c) 42 × 25 + 36 × 87 + 42 × 11 – 36 × 29
= 42 × (25 + 11) + 36 × (87 – 29)
= 42 × 36 + 36 × 58
= 36 × (42 + 58)
= 36 × 100
= 3600
a] 57 .192 +192 . 32 + 11 .192
= 192.[57 + 32 + 11]
=192 . 100
= 19200
b]38 . 75 +38 .26 – 38
= 38 . 75 + 38 .26 – 38 . 1
= 38. [75 +26 – 1]
= 38 . 100
= 3800
c]42 .25 + 36 .87 +42 .11 – 36 . 29
=42 . 25 + 42 . 11 + 36 .87 – 36 . 29
=42 . [25 + 11] + 36 .[ 87 – 29]
= 42 . 36 + 36 . 58
= 36 . [ 42 + 58]
= 36 . 100
= 3600
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