[(1+2019/1)+(1+2019/2)+...+(1+2019/1020)]:[(1+1020/1)(1+1020/2)+....+(1+1020/2019)]
Mik sắp nộp r ai nhanh mik tick liền lun miễn là bài làm tốt 👍
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2020 × 2021 - 1000 - 2020 × 2019 - 1020
= 2020 × 2021 - 2020 × 2019 - 1000 - 1020
= 2020 × 2021 - 2020 × 2019 - (1000 + 1020)
= 2020 × 2021 - 2020 × 2019 - 2020
= 2020 × 2021 - 2020 × 2019 - 2020 × 1
= 2020 × (2021 - 2019 - 1)
= 2020 × 1
= 2020.
1)1-2+3-4+5-6+...+1019-1020 (có 1020 số hạng)
= (1-2+3-4) + (5-6+7-8) +.....+(1017-1018+1019-1020) (có 225 nhóm)
= -2 +(-2) +...........+(-2) ( có 225 số hạng)
= -2.225
= -450
5)1+2-3-4+...+97+98-99-100
= (1+2-3-4) +..........+(97+98-99-100)
= (-4) +..........(-4)
= (-4). 25
= -100
2)(-1)+2+(-3)+4+...+(-99)+100
= -1 +2 -3+4+.....-99+100
= (2-1) +(4-3) +....+(100-99) ( Có 50 cặp )
= 1+ 1+...+1 ( Có 50 số )
=1.50
=50
4) Nếu đổi +48 thành -48 thì mik làm đc
2-4+6-8+...-48-50
= 2+ (6-4) + (10-8) + ...+(50-48)
=2+2+2+....+2
=2.13
=26
\(1020+Xx\frac{1}{3}=\frac{4}{5}+1020\)
\(=1020+Xx\frac{1}{3}=\frac{5104}{5}\)
\(=Xx\frac{1}{3}=\frac{5104}{5}-1020\)
\(=Xx\frac{1}{3}=\frac{4}{5}\)
\(=\frac{4}{5}:\frac{1}{3}\)
\(=\frac{12}{5}\)
\(1020+x.\frac{1}{3}=\frac{4}{5}+1020\)
\(1020+x.\frac{1}{3}=\frac{5104}{5}\)
\(x.\frac{1}{3}=\frac{5104}{5}-1020\)
\(x.\frac{1}{3}=\frac{4}{5}\)
\(x=\frac{4}{5}:\frac{1}{3}\)
\(x=\frac{12}{5}\)
♥ ☼ ↕ ✿ ⊰ ⊱ ✪ ✣ ✤ ✥ ✦ ✧ ✩ ✫ ✬ ✭ ✯ ✰ ✱ ✲ ✳ ❃ ❂ ❁ ❀ ✿ ✶ ✴ ❄ ❉ ❋ ❖ ⊹⊱✿ ✿⊰⊹ ♧ ✿
\(A=\frac{2019^{2020}+1}{2019^{2021}+1}\)và \(B=\frac{2019^{2018}+1}{2019^{2019}+1}\)
Xét \(A=\frac{2019^{2020}+1}{2019^{2021}+1}\Rightarrow2019A=\frac{2019^{2021}+2019}{2019^{2021}+1}=1+\frac{2019}{2019^{2021}+1}\)
Xét \(B=\frac{2019^{2018}+1}{2019^{2019}+1}\Rightarrow2019B=\frac{2019^{2019}+2019}{2019^{2019}+1}=1+\frac{2018}{2019^{2019}+1}\)
Vì \(1+\frac{2018}{2019^{2021}+1}< 1+\frac{2018}{2019^{2019}+1}\Rightarrow\frac{2019^{2020}+1}{2019^{2021}+1}< \frac{2018^{2019}+1}{2019^{2019}+1}\)
\(\Rightarrow A< B\)
Ta có:
\(A=\frac{2019^{2020}+1}{2019^{2021}+1}\)
\(\Rightarrow2019A=\frac{2019^{2021}+2019}{2019^{2021}+1}\)
\(\Rightarrow2019A=1+\frac{2019}{2019^{2021}+1}\)
\(\Rightarrow A=1+\frac{2019}{2019^{2021}+1}:2019\)
Ta lại có:
\(B=\frac{2019^{2018}+1}{2019^{2019}+1}\)
\(\Rightarrow2019B=\frac{2019^{2019}+2019}{2019^{2019}+1}\)
\(\Rightarrow2019B=1+\frac{2019}{2019^{2019}+1}\)
\(\Rightarrow B=1+\frac{2019}{2019^{2019}+1}:2019\)
Do \(2019^{2021}+1>2019^{2019}+1\)
\(\Rightarrow\frac{2019}{2019^{2021}+1}< \frac{2019}{2019^{2019}+1}\)
\(\Rightarrow1+\frac{2019}{2019^{2021}+1}:2019< 1+\frac{2019}{2019^{2019}+1}:2019\)
\(\Rightarrow A< B\)
Vậy \(A< B.\)