Vì sao bằng nhau ạ?? Xin hãy cho giải thích kỹ ak
a : 2008 × 2010 < 2009 × 2009
b : 2020 × 2020 < 2021 × 2021
a, 2008 \(\times\) 2010 = (2009 - 1)\(\times\) (2009 + 1) = 2009\(\times\)2009- 2009+2009-1
2008 \(\times\) 2010 = 2009 \(\times\) 2009 - 1 < 2009 \(\times\) 2009
Câu b, làm tương tự
A) \(...=2008.\left(2009+1\right)=2008.2009+2008\left(1\right)\)
\(2009.2009=2009.\left(2008+1\right)=2008.2009+2009\left(2\right)\)
\(\left(1\right).\left(2\right)\Rightarrow2008.2010< 2009.2009\)
B) \(2020.2022=2020.\left(2021+1\right)=2020.2021+2020\left(1\right)\)
\(2021.2021=2021.\left(2020+1\right)=2020.2021+2021\left(2\right)\)
\(\left(1\right).\left(2\right)\Rightarrow2020.2022< 2021.2021\)