Answer:
[tex]\sqrt{19} - 4 \\or\\ - \sqrt{19} - 4[/tex]
Step-by-step explanation:
[tex]x^2+8x-3=0 \Rightarrow x^2+2.4.x+16-19=0\\\Rightarrow (x+4)^2=19 \\Then\\ x+4 = \sqrt{19} \Rightarrow x= \sqrt{19} - 4 \\or\\x+4 = -\sqrt{19} \Rightarrow x= -\sqrt{19} - 4[/tex]
