The answers are B. 2 square root of 5 and C. − 2 square root of 5.
[tex]4 x^{2} -3=77[/tex]
[tex]4 x^{2} =77+3[/tex]
[tex]4 x^{2} =80[/tex]
[tex] x^{2} =80:4[/tex]
[tex] x^{2} =20[/tex]
[tex]x= \sqrt{20} [/tex]
[tex]x= \sqrt{4*5}[/tex]
[tex]x= \sqrt{4}* \sqrt{5} [/tex]
Since √4 could be either -2 or +2, the solutions are:
[tex]x=2 \sqrt{5} [/tex] or [tex]x=-2 \sqrt{5} [/tex]
