3x² - 36 = 0
3x² = 36
x² = 36 : 3 = 12
x₁,₂ = ±√12 = ±2√3
√3 · x² - √81 = 0
√3 · x² = √81
x² = √81 : √3 = √27 = 3√3
x₁ = [tex]\sqrt{3\sqrt{3}}=\sqrt{3*3^{\frac{1}{2}}}=\sqrt{3^{\frac{3}{2}}}=3^{\frac{3}{4}}[/tex], x₂ = [tex]-\sqrt{3\sqrt{3}}=-\sqrt{3*3^{\frac{1}{2}}}=-\sqrt{3^{\frac{3}{2}}}=-3^{\frac{3}{4}}[/tex]
9x² + 81 = 0
9x² = -81
x² = -81 : 9 = -9
x₁ = [tex]\sqrt{-9}=\sqrt{-1}*\sqrt{9}=3i[/tex], x₂ = [tex]-\sqrt{-9}=-\sqrt{-1}*\sqrt{9}=-3i[/tex]
/robertinni
