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222-9+11+12:2*14+14 = ? ( )

## Toán Lớp 5: bài 1 : a, 45 x 113 + 45 x 113 + 113 b,54 x 47 – 47 x 53 – 20 – 27 c, ( 145 x 99 + 145 ) – ( 143 x 101 – 143)

Toán Lớp 5: bài 1 :
a, 45 x 113 + 45 x 113 + 113
b,54 x 47 – 47 x 53 – 20 – 27
c, ( 145 x 99 + 145 ) – ( 143 x 101 – 143)

1. a,
45 × 113 + 45 × 113 + 113
= (45 + 45 + 1) × 113
= 91 × 113
= 10283
b,
54 × 47 – 47 × 53 – 20 – 27
= 54 × 47 – 47 × 53 – (20 + 27)
= 54 × 47 – 47 × 53 – 47
= (54 – 53 – 1) × 47
= 0 × 47
= 0
c,
(145 × 99 + 145) – (143 × 101 – 143)
= [145 × (99 + 1)] – [143 × (101 – 1)]
= 145 × 100 – 143 × 100
= (145 – 143) × 100
= 2 × 100
= 200

2. a) 45 xx 113 + 45 xx 113 + 113
= 113 xx ( 45 + 45+ 1)
= 113 xx 91
= 10283
———————————–
b) 54 xx 47 – 47 xx 53 – 20 – 27
= 54 xx 47 – 47 xx 53 – ( 20 + 27)
= 54 xx 47 – 47 xx 53 – 47
= 47 xx ( 54 – 53 – 1)
= 46 xx 0
= 0
—————————————-
c) ( 145 xx 99 + 145) – (143 xx 101 – 143)
= ( 145 xx 99 + 145 xx 1) – ( 143 xx 101 – 143 xx 1)
= [145 xx ( 99 + 1) ] – [143xx ( 101 – 1)]
= [ 145 xx 100] – [ 143 xx 100]
= 14500 – 14300
= 200