a) x2 +2x +1 -2x +6
=x2 + 7
b) 2x2 +x +x2-1 -x
= 3x2 -1
\(a)x^2+\left(2a-2\right)x+a+6\)
\(b)x^2+2x\)
a, \(\left(x+1\right)^2-2\left(x-3\right)=x^2+2x+1-2x+6=x^2+7\)
b, \(x\left(2x+1\right)+\left(x-1\right)\left(x+1\right)-x=2x^2+x+x^2-1-x\)
\(=3x^2-1=\left(\sqrt{3}x-1\right)\left(\sqrt{3}x+1\right)\)