Question

Resolva as equações do 2o grau com as fórmulas de delta e de Bháskara. a) x 2 – 4x +3 = 0 b) x 2 – 4x - 12 = 0 c) x 2 – 9x + 20= 0 d) x 2 – 6x +7 = 0

Answer 1

Explicação passo-a-passo:

a) x 2 – 4x +3 = 0

a=1 b= -4 c= 3

¤=b^2-4.a.c

¤= -4^2-4.1.3

¤=16-12

¤=4

x= -b+_V¤/2.a

x= -(-4)+_V4/2.1

x=4+_2/2

x'= 4+2/2 = 6/2= 3

x"= 4-2/2 2/2= 1

b) x 2 – 4x - 12 = 0

a= 1 b= -4 c -12

¤= b^2-4.a.c

¤= -4^2-4.1.-12

¤=16+48

¤=64

x= -b+_V¤/2.a

x= -(-4)+_8/2.1

x=4+_8/2

x'=4+8/2= 12/2 = 6

x"= 4-8/2 = -4/2 = -2

c) x 2 – 9x + 20= 0

a=1 b= -9 c= 20

¤= b^2-4.a.c

¤=-9^2-4.1.20

¤=81-80

¤=1

x= -b+_V¤/2.a

x= -(-9)+_V1/2.1

x=9+_1/2

x'=9+1/2 = 10/2 = 5

x"=9-1/2 = 8/2 = 4

d) x 2 – 6x +7 = 0

a= 1 b= -6 c= 7

¤= b^2-4.a.c

¤= -6^2-4.1.7

¤= 36-28

¤=8