Question

Resolva as equações do 2° grau

a) 7x²-21=0

b)x²+9=0

c)x²-49=0

d)5x²-20=0

Answer 1

a)  7x²-21=0 --> 7x² = 21 --> x² = 21/7 --> x² = 3 --> x = √3

b) x²+9=0 --> x² = -9 --> x = √-9 --> x = 3i

c) x²-49=0 --> x² = 49 --> x = √49 --> x = 7

d) 5x²-20=0 --> 5x² = 20 --> x² = 20/5 --> x² = 4 --> x = √4 --> x = 2