Question

Tính hợp lý:

a, 52 – 42 + 37 – 28 + 38 + 63

b, 130 + 35.19 – 9.70 – 30

c, (11 + 13 + 15 + … + 19).(6.8 – 48)

d, (72 – 8.9):(20+22+24 – 19 +21+23) 

Answer 1

a) 52 – 42 + 37 – 28 + 38 + 63 = (52 – 42) + (37 + 63) + (38 – 28) = 10 + 100 + 10 =  120

b) 130 + 35.19 – 9.70 – 30

= (35.19 – 9.70) + (130 – 30) = (35.19 – 9.35.2) + 100 = 35.(19 – 18) + 100 = 35 + 100 = 135

c) (11 + 13 + 15 + … + 19).(6.8 – 48) = (11+13+15+…+19).0 = 0

d) (72 – 8.9):(20+22+24 – 19 +21+23) = 0:(20+22+24 – 19 +21+23) = 0