Question

Uma das raizes da equaçao x^2-6x+25=0 é : a) -3-4i b) 3-4i c) -4-3i d) -3+4i e) 4+3i

Answer 1

$x^{2}-6x+25 = 0 \\\\ \Delta = b^{2}-4 \cdot a \cdot c \\\\ \Delta = (-6)^{2}-4 \cdot (1) \cdot (25) \\\\ \Delta = 36-100 \\\\ \Delta = -64 \\\\\\ x = \frac{-b \pm \sqrt{\Delta}}{2a} \\\\ x = \frac{-(-6) \pm \sqrt{-64}}{2 \cdot 1} \\\\ x = \frac{6 \pm \sqrt{64 \cdot i^{2}}}{2} \\\\\ x = \frac{6 \pm 8i}{2} \\\\\\ x' = \frac{6 + 8i}{2} = \boxed{3+4i} \\\\ x'' = \frac{6 - 8i}{2} = \boxed{3-4i} \\\\\\ \boxed{\boxed{S = \{3+4i, \ 3-4i\}}}$

Letra B