a=2020. 2020-2022.2018 b= (1/4 -1).(1/9-1).(1/16-1)….(1/400-1) 09/08/2021 Bởi Kennedy a=2020. 2020-2022.2018 b= (1/4 -1).(1/9-1).(1/16-1)….(1/400-1)
Đáp án: Giải thích các bước giải: a=2020. 2020-2022.2018a= 2020.(2022-2) – 2022.(2020-2)a=2020.2022-2.2020 – 2022.2020+2022.2a=2.(2022-2020)=2.2=4 Bình luận
Ta có : A = 2020 . 2020 – ( 2020 + 2 ) . 2018 A = 2020 . 2020 – 2018 . 2020 – 2018 . 2 = 2020 . ( 2020 – 2018 ) – 2018 .2 A = 2 . ( 2020 – 2018 ) = 2 . 2 = 4 B = -3/4 . -8/9 . -15/16….-399/400 =( -1 ) ^19 .1.3/2.2 . 2.4/3.3 .3.5/4.4 …. 19.21/20.20 =( -1). (1.2.3….19).(3.4.5…21)/(2.3.4….20).(2.3.4….20) =( -1 ) . 1.21/20.2 = -21/40 XIN HAY NHẤT Ah Bình luận
Đáp án:
Giải thích các bước giải:
a=2020. 2020-2022.2018
a= 2020.(2022-2) – 2022.(2020-2)
a=2020.2022-2.2020 – 2022.2020+2022.2
a=2.(2022-2020)=2.2=4
Ta có :
A = 2020 . 2020 – ( 2020 + 2 ) . 2018
A = 2020 . 2020 – 2018 . 2020 – 2018 . 2 = 2020 . ( 2020 – 2018 ) – 2018 .2
A = 2 . ( 2020 – 2018 ) = 2 . 2 = 4
B = -3/4 . -8/9 . -15/16….-399/400
=( -1 ) ^19 .1.3/2.2 . 2.4/3.3 .3.5/4.4 …. 19.21/20.20
=( -1). (1.2.3….19).(3.4.5…21)/(2.3.4….20).(2.3.4….20)
=( -1 ) . 1.21/20.2 = -21/40
XIN HAY NHẤT Ah