Răspuns:
Explicație pas cu pas:
a)
a = 2021 - (2020 - 1)
a = 2021 - 2019
a = 2
b = 2021 - 2020 - 1
b = 1 - 1
b = 0
2 > 0 ⇔ a > b
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b)
x = 7 + 9 + 11 + ..... + 209
( 209 - 7) : 2 + 1 = 202 : 2 + 1 = 102 termeni are suma
x = 102 × ( 7+209) : 2
x = 51 × 216
y = 102 + 102 + 102 + ........ + 102 ( 108 termeni)
y = 108 × 102
y = 2 × 51 × 108
y = 51 × 216
51 × 216 = 108 × 102 ⇔ x = y
