Answer:
x = ± 2i[tex]\sqrt{6}[/tex]
Step-by-step explanation:
Given
3x² + 40 = - x² - 56 ( add x² to both sides )
4x² + 40 = - 56 ( subtract 40 from both sides )
4x² = - 96 ( divide both sides by 4 )
x² = - 24 ( take the square root of both sides )
x = ± [tex]\sqrt{-24}[/tex]
= ± [tex]\sqrt{4(6)(-1)}[/tex] → note [tex]\sqrt{-1}[/tex] = i
= ± 2i[tex]\sqrt{6}[/tex]
