Toán Lớp 5: bài 1 : a, ( 72 – 8 x 9 ) : ( 20 + 21 + -..+ 101) b, ( 500 x 9 – 250 x 18 ) x ( 1 + 2 +-…+ 99 ) c, ( m : 1 + m x 1 ) : m x 20

0 bình luận về “Toán Lớp 5: bài 1 : a, ( 72 – 8 x 9 ) : ( 20 + 21 + -..+ 101) b, ( 500 x 9 – 250 x 18 ) x ( 1 + 2 +-…+ 99 ) c, ( m : 1 + m x 1 ) : m x 20”

1. ( 72 – 8 × 9 ) : ( 20 + 21 + ……+ 101)

   = ( 72 – 72 ) : ( 20 + 21 + ……+ 101)

   = 0 : ( 20 + 21 + ……+ 101)

   = 0

   ( 500 × 9 – 250 × 18 ) × ( 1 + 2 +…….+ 99 )

   = ( 250 × 2 × 9 – 250 × 18 ) × ( 1 + 2 +…….+ 99 )

   = (250 × 18 – 250 × 18 ) × ( 1 + 2 +…….+ 99 )

   = 0 × ( 1 + 2 +…….+ 99 )

   = 0

   ( m : 1 + m × 1 ) : m × 2021 + m + 2021 (m là STN)

   = ( m + m ) : m × 2021 + m + 2021

   = 2 × m : m  × 2021 + m + 2021

   = 2  × 2021 + m + 2021

   = 4042 + m + 2021

   = 6063 + m

   (Chúc bạn học tốt)

    

2. Giải đáp:

   a)=0

   b)=0

   c)=6063+m

   Trình bày lời giải:

   a)
    ( 72 – 8 xx 9 ) : ( 20 + 21 + …+ 101)
   =(72-72):(20+21+…+101)
   =0:(20+21+…+101)
   =0
   b)
   ( 500 xx 9 – 250 xx 18 ) xx ( 1 + 2 +…+ 99 )
   =(4500-4500)xx(1+2+…+99)
   =0xx(1+2+…+99)
   =0
   c)
   (m:1+mxx1):mxx2021+m+2021
   =(mxx1+mxx1):mxx2021+m+2021
   =mxx2:mxx2021+m+2021
   =(mxx1/m)xx(2xx2021)+m+2021
   =1xx4042+m+2021
   =4042+2021+m
   =6063+m