20212 cái này là \(2021^2\) nha!

2020.2022=(2021−1)(2021+1)=20212−1<\(2021^2\)

\(\Rightarrow2020.2021.2022< 2021^2.2021=2021^3\)

\(a,156-\left(x+61\right)=82\\ x+61=74\\ x=13\\ b,\left(x-35\right)+24=4\\ x-35=-20\\ x=15\\ c,124+\left(118-x\right)=217\\ 118-x=93\\ x=25\)

\(a,-21\\ b,-10\\ c,52\)

\(c,135.3^2-3^2.130\\ =3^2\left(135-130\right)\\ =9.5=45\)