Question

resolva aas equações do 2 grau em IR.

a)x2-90=31
b)x2-200=200
c)5x2+4=49
d)9x2=25+8x2
e)x2=99-10x2
f)2x2+11=x2+12
g)5(x2-1)=4(x2+1)
h)x(x+2)=2x+25

Answer 1

a)x²-90=31

x² = 31+90

x² = 121

x = ± 11

x’ = 11 e x” = -11

 

b)x²-200=200

x² = 200 – 200

x= 0

 

c)5x²+4=49

5x² = 49-4

x² = 45/5

x² =  9

x = ±3

x’ = 3 e x” = -3

 

d)9x²=25+8x²

9x² - 8x² = 25

x² = 25

x = ±5

x’ = 5 e x” = -5

 

e)x²=99-10x²

x² + 10x² = 99

11x² = 99

x² = 9

x = ±3

x’ = 3 e x” = -3

 

f)2x²+11=x²+12

2x² - x² = +12 – 11

x² = 1

x = ±1

x’ = 1 e x” = -1

 

g)5(x²-1)=4(x2+1)

5x² - 5 = 4x² +4

5x² - 4x² =  +4 +5

x² = 9

x = ±3

x’ = 3 e x” = -3

 

h)x(x+2)=2x+25

x² + 2x = 2x + 25

x² =  2x + 25 - 2x

x² =  25

x = ±5

x’ = 5 e x” = -5