Tìm số nguyên n sao cho:
a) (-2019)(n+1) < 0 b) 2020(n- 4) < 0
c) 2021( n-1) > 0 d) (-2022) (n-2) > 0
Tìm số nguyên n sao cho:
a) (-2019)(n+1) < 0 b) 2020(n- 4) < 0
c) 2021( n-1) > 0 d) (-2022) (n-2) > 0
Đáp án:
a) (-2019)(n+1) < 0
=> n + 1 > 0
=> n > -1
b) 2020(n- 4) < 0
=> n – 4 < 0
=> n < 4
c) 2021( n-1) > 0
=> n – 1 > 0
=> n > 1
d) (-2022) (n-2) > 0
=> n – 2 < 0
=> n < 2
Giải thích các bước giải:
a) (-2019)(n+1) < 0
=> n + 1 > 0
=> n > -1
b) 2020(n- 4) < 0
=> n – 4 < 0
=> n < 4
c) 2021( n-1) > 0
=> n – 1 > 0
=> n > 1
d) (-2022) (n-2) > 0
=> n – 2 < 0
=> n < 2
a) (-2019)(n+1) < 0
<=> n + 1 > 0
<=> n > -1
b) 2020(n- 4) < 0
<=> n – 4 < 0
<=> n < 4
c) 2021( n-1) > 0
<=> n – 1 > 0
<=> n > 1
d) (-2022) (n-2) > 0
<=> n – 2 < 0
<-> n < 2