Question

Answer 1

Câu 2: 

a: =100²=10000

Answer 2

Câu 2:

\(a,=75^2+2.75.25+25^2=\left(72+25\right)^2=100^2=10000\\ b,=2019\left(2019-19\right)-10\left(19+1981\right)=2019.2000-10.2000=2009.2000=4018000\)

Câu 3:

\(a,\Leftrightarrow15x-5x^2+5x+5x^2=40\Leftrightarrow20x=40\Leftrightarrow x=2\\ b,\Leftrightarrow\left(x-3\right)\left(x-3-1\right)=0\Leftrightarrow\left(x-3\right)\left(x-4\right)=0\Leftrightarrow\left[{}\begin{matrix}x=3\\x=4\end{matrix}\right.\)