Answer:
3x^2 +2x
9x^2 +6x+1
Step-by-step explanation:
[tex](3x +1)\cdot 2x - x^2 \cdot 3\\\\=2x\left(3x+1\right)-3x^2\\\\\mathrm{Expand}\:2x\left(3x+1\right):\quad 6x^2+2x\\\\=6x^2+2x-x^2\cdot \:3\\\\\mathrm{Simplify}\:6x^2+2x-x^2\cdot \:3:\\\quad 3x^2+2x[/tex]
2.
[tex](3x + 1)^2\\\\\mathrm{Apply\:Perfect\:Square\:Formula}:\\\quad \left(a+b\right)^2=a^2+2ab+b^2\\\\a=3x,\:\:b=1\\\\=\left(3x\right)^2+2\cdot \:3x\cdot \:1+1^2\\\\\mathrm{Simplify}\:\left(3x\right)^2+2\cdot \:3x\cdot \:1+1^2:\\\quad 9x^2+6x+1[/tex]
