6x² + 12x - 21
3(2x² + 4x - 7)
2x² + 4x - 7 ⇒ This is the factorised answer
This is how you solve it:
[tex] Solve\ using\ formular \ \ \ \boxed{ x={ \frac{-b\pm \sqrt{b^2-4ac} }{2a} }} \\ x={ \frac{-4\pm \sqrt{4^2-4(2)(-7)} }{2(2)} } \\ x={ \frac{-4\pm \sqrt{72} }{4} } \\ \\ x=1.12132\ \ \ or\ \ \ x=3.12132 [/tex]
