Question

me ajudem
resolva as equações de 2 grau

a) 4x²-9=0
b)7x²-42 =0
c)x²+5=0
d)x²-64=0
e)5x²-25=0

Answer 1

$a) \\ 4x^2-9=0 \\ 4x^2=9 \\ \\ x^2= \frac{9}{4} \\ \\ x=\pm \sqrt{ \frac{9}{4} } \\ \\ x=\pm \frac{3}{2} \\ \\ S=\{- \frac{3}{2} ,+ \frac{3}{2} \} \\ \\ b) \\ 7x^2-42=0 \\ 7x^2=42 \\ x^2=42\div7 \\ x^{2} =6 \\ \\ x=\pm \sqrt{6} \\ \\ S=\{- \sqrt{6} ,+ \sqrt{6} \}$


$c) \\ x^2+5=0 \\ x^{2} =-5 \\ x=\pm \sqrt{-5} ~~ n/existe \\ \\ S=\emptyset~~conjunto~~ vazio \\ \\ d) \\ x^2-64=0 \\ x^{2} =64 \\ x=\pm \sqrt{64} \\ x=\pm8 \\ \\ S=\{-8,+8\} \\ \\ e) \\ 5x^2-25=0 \\ 5x^2=25 \\ x^2=25\div5 \\ x^2=5 \\ x=\pm \sqrt{5} \\ \\ S=\{- \sqrt{5},+ \sqrt{5} \}$