Tính nhanh

2020×28+74×2020-4040

= 2020 x 28 + 74 x 2020 - 2020 x 2

= 2020 x (28+74 - 2)

= 2020 x 100

= 202 000

I don't now 

sorry 

...................

nha

   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.

 2019 . 2021 - 2020. 2020

= 2019(2020+1) - 2020( 2019+1)

= 2019 .2020 + 1.2019 - 2020.2019 + 1.2020

= 2019 -2020

= -1

\(2019.2021-2020.2020\)

\(=2019\left(2020+1\right)-2020\left(2019+1\right)\)

\(=2019.2020+2019-2020.2019+2020\)

\(=2019-2020\)

\(=-1\)

    2019 . 2021 - 2020 . 2020

= 2019 . ( 2020 + 1 ) - 2020 . ( 2019 + 1 )

= 2019 . 2020 + 2019 . 1 - 2020 . 2019 + 2020 .1

= (2019 . 2020 - 2020 . 2019 ) +  ( 2019 . 1 - 2020 . 1 )

= 0 + ( -1 )

= -1

= 1

À câu này giải theo cách này e nhé!

E tham khảo nha:(-- được xem là +)

=>(2020+27)+(2020-73)-129

=2047+1947-129=3865

=2000 x 2010 x 2020 x 2030 x 2040/2010 x 2020 x 2030 x 2040 x 2050

=2000/2050 = 40/41

Tí cậu gạch 2010;2020;2030;2040;2050 cả trên cả dưới nhé. Tớ ko biết ấn vào đâu để gạch

2000/2010 x 2010/2000 x 2020/2030 x 2030/2040 x 2040/50

=1/1 x 1/1 x 202/203

=202/203

\(t=\frac{2009.2010+2000}{2011.2010-2020}\)

\(t=\frac{2009.2010+2000}{\left(2009+2\right).2010-2020}\)

\(t=\frac{2009.2010+2000}{2009.2010+2.2010-2020}\)

\(t=\frac{2009.2010+2000}{2009.2010+2000}=1\)

\(q=\frac{\text{2014.2015+2010}}{2016.2015-2020}\)

\(q=\frac{\text{2014.2015+2010}}{\left(2014+2\right).2015-2020}\)

\(q=\frac{\text{2014.2015+2010}}{2014.2015+2.2015-2020}\)

\(q=\frac{\text{2014.2015+2010}}{\text{2014.2015+2010}}=1\)