a,
\(2018^2-2017\cdot2019\\ =2018^2-\left(2018-1\right)\left(2018+1\right)\\ =2018^2-2018^2+1\\ =1\)
b, Đề khó nhìn bạn ạ, gõ Latex đi bạn! :)
a) 2018^2-2017.2019
= 2018^2 -(2018-1)(2018+1)
= 2018^2 -2018^2 -1
=-1
a.\(2018^2-2017\cdot2019\)
\(=2018^2-\left(2018-1\right)\cdot\left(2018+1\right)\)
\(=2018^2-\left(2018^2-1\right)\)
\(=2018^2-2018^2+1\)
=1
b.\(2018^3+\frac{1}{2018-2017}\)
\(=2018^3+1\)
nếu thích thì hằng đẳng thức cho vui
a) \(2018^2-2017.2019\)
\(=2018^2-\left(2018-1\right).\left(2018+1\right)\)
\(=2018^2-\left(2018^2-1\right)\)
\(=2018^2-2018^2+1\)
\(=\left(2018-2018\right).\left(2018+2018\right)+1\)
\(=0.4036+1\)
\(=1.\)
b) \(2018^3+\frac{1}{2018-2017}\)
\(=2018^3+1\)
\(=2018^3+1^3\)
\(=\left(2018+1\right).\left(2018^2-2018.1+1\right)\)
\(=\left(2018+1\right).\left(4072324-2018+1\right)\)
\(=2019.4070307\)
\(=8217949833.\)
Chúc bạn học tốt!
