Solve the inequation $\displaystyle (x^2+3x+1)(x^2+3x-3)\ge 5$

on opening the brackets i got

$\displaystyle x^2(x^2+3x-3)+3x(x^2+3x-3)+1(x^2+3x-3)\ge 5$

$\displaystyle x^4+3x^3-3x^2+3x^3+9x^2-9x+x^2+3x-3-5\ge 0$

$\displaystyle x^4+6x^3+7x^2-6x-8\ge 0$

am i right??

after that what should i do??