tính a , 39 . 76 + 39 . 23 + 39 b, 67. 58 +67. 43 – 67 c, 28. ( 231 + 69 ) + 72 . ( 231 + 69 ) d, 1 + 2 – 3 -4 + 5 + 6 – 7 – 8 +…..- 299 – 300 + 301

0 bình luận về “tính a , 39 . 76 + 39 . 23 + 39 b, 67. 58 +67. 43 – 67 c, 28. ( 231 + 69 ) + 72 . ( 231 + 69 ) d, 1 + 2 – 3 -4 + 5 + 6 – 7 – 8 +…..- 299 – 300 + 301”

1. a , 39 × 76 + 39 × 23 + 39

   =39 × 76 + 39 × 23 + 39×1

   =39×(76+23+1)

   =39×100

   =3900

   b, 67×58 +67×43 – 67

   67×58 +67× 43 – 67×1

   67×(58+43-1)

   =67×100

   =6700

   c, 28× ( 231 + 69 ) + 72 × ( 231 + 69 )

   28×300+72×300

   =300×(28+72)

   =300×100

   =30 000

   d, 1+2-3-4+ 5 + 6 – 7 – 8 +…..- 299 – 300 + 301 + 302

   1+(2-3-4+5)+(6-7-8+9)+…+(298-299 – 300 + 301)+302

   =1+0+0+…………+0+302

   =0+(1+302)

   =0+303

   =303

   Trả lời

2. a, 39 . 76 + 39 . 23 + 39

   =39.(76+23+1)

   =39.100

   =3900

   b, 67. 58 +67. 43 – 67

   =67.(58+43-1)

   =67.100

   =6700

   c, 28. ( 231 + 69 ) + 72 . ( 231 + 69 )

   =(231+69).(28+72)

   =300.100

   =30000

   d, 1 + 2 – 3 -4 + 5 + 6 – 7 – 8 +…..- 299 – 300 + 301 + 302 (302 số hạng)

   =(1+2-3-4)+(5+6-7-8)+…+(297+298-299-300)+301+302

   =(-4)+(-4)+…+(-4)+301+302 (có 75 số -4)

   =(-4).75+603

   =-300+603

   =303

    

   Trả lời