Answer:
x=-8 or x=-1 (first option)
Step-by-step explanation:
[tex]\sqrt{1-3x}=x+3\\1-3x=(x+3)^{2} \\[/tex]
now expand the bracket on the right
[tex]1-3x=x^{2} +6x+9\\simplify:\\1-9=x^2+6x+3x\\-8=x^2+9x\\[/tex]
now make it a quadratic equation:
[tex]x^2+9x+8=0\\factorise:\\(x+1)(x+8)\\so:\\x+1=0 \\x=-1\\\\and \\x+8=0\\x=-8[/tex]
