Question

resolva as equações do 2° grau
• 9x² -3x=0

• x² -4=0

• -x² -x=0

• 7x² -10=0

•9y² -12y +4=0
​

Answer 1

Explicação passo-a-passo:

• 9x² -3x=0

x.(9x-3)=0

x=0

9x-3=0

9x=3

x=3/9 =(3÷3)/(9÷3)= 1/3

S={( 0, 1/3)}

• x² -4=0

x²=4

x=√4

x=±2

S={( -2 , +2)}

• -x² -x=0

x.(-x-1)=0

x=0

-x-1=0

-x=+1

x=+1/-1

x=-1

S={( 0, -1)}

• 7x² -10=0

7x²=10

x²=10/7

x=±√10/7

x'= -√70/7 ou x"= +√70/7

•9y² -12y +4=0

a=9

b=-12

c=4

∆=b²-4.a.c

∆=(-12)²-4.(9).(4)

∆=144-144

∆=0

x'=x"=-b/2a= -(-12)/2.(9)

x'=x"=12/18

x'=x"=(12÷6)/(18÷6)

x'=x"=2/3

S={( 2/3 )}