a) Ta có: \(\left(x^2+3x+1\right)\left(x^2+3x+2\right)-6\)
\(=\left(x^2+3x\right)^2+3\left(x^2+3x\right)+2-6\)
\(=\left(x^2+3x\right)^2+4\left(x^2+3x\right)-\left(x^2+3x\right)-4\)
\(=\left(x^2+3x\right)\cdot\left(x^2+3x+4\right)-\left(x^2+3x+4\right)\)
\(=\left(x^2+3x+4\right)\left(x^2+3x-1\right)\)
b)Sửa đề: \(a^3+2a-3\)
Ta có: \(a^3+2a-3\)
\(=a^3-a^2+a^2-a+3a-3\)
\(=a^2\left(a-1\right)+a\left(a-1\right)+3\left(a-1\right)\)
\(=\left(a-1\right)\left(a^2+a+3\right)\)
c) Ta có: \(a^3-3a+2\)
\(=a^3-a-2a+2\)
\(=a\left(a^2-1\right)-2\left(a-1\right)\)
\(=a\left(a-1\right)\left(a+1\right)-2\left(a-1\right)\)
\(=\left(a-1\right)\left(a^2+a-2\right)\)
\(=\left(a-1\right)\left(a^2+2a-a-2\right)\)
\(=\left(a-1\right)\left[a\left(a+2\right)-\left(a+2\right)\right]\)
\(=\left(a+2\right)\cdot\left(a-1\right)^2\)
nhờ mn là giúp mình với ạ , minh đang cần gấp :( 
