\(1,\\ a,=2005x^2+4010\\ b,=7x^2-x-14x+2=7x^2-15x+2\\ c,=25x^2-30x+9-25x^2=9-30x\\ 2,\\ a,\Leftrightarrow2x^2-x-2x^2=2021\\ \Leftrightarrow x=-2021\\ b,\Leftrightarrow\left(x-2\right)^2=0\Leftrightarrow x-2=0\Leftrightarrow x=2\)
câu 1:
a) \(=2005x^2+4010x\)
b) \(\left(x-2\right)\left(7x-1\right)=7x^2-14x-x+2=7x^2-15x+2\)
c) \(=\left(5x-3-5x\right)\left(5x-3+5x\right)=-3\left(10x-3\right)\)
câu 2:
a) \(\Leftrightarrow2x^2-x-2x^2=2021\\ \Leftrightarrow-x=2021\\ \Leftrightarrow x=-2021\)
b) \(\Leftrightarrow\left(x-2\right)^2=0\\ \Leftrightarrow x=2\)
Câu 1:
a) \(2005x\left(x+2\right)=2005x^2+4010x\)
b) \(\left(x-2\right)\left(7x-1\right)=7x^2-15x+2\)
c) \(\left(5x-3\right)^2-25x^2=25x^2-30x+9-25x^2=-30x+9\)
Câu 2:
a) \(\Rightarrow2x^2-x-2x^2=2021\Rightarrow x=-2021\)
b) \(\Rightarrow\left(x-2\right)^2=0\Rightarrow x=2\)
