Question

Resolva as equçoes de 2 grau
A x²-90=31
B 5x²+4=49
C 4x²-27=x²
D 2x²+11=x²+12
E 5(x²-1)=4(x²+1)
F x(x+2)=2x+25

Answer 1

a)
 x² - 90 = 31
x² = 31 + 90
x² = 121
x = √121
x = + 11 e x = - 11

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b)
 5x² + 4 = 49
5x² = 49 - 4
5x² = 45
x² = 45/5
x² = 9
x = √9
x = + 3 e x = - 3

***************************

c)

4x² - 27 = x²
4x² - x² = 27
3x² = 27
x² = 27/3
x² = 9
x = √9
x = + 3 e x = - 3

*****************************
d)
2x² + 11 = x² + 12
2x² - x² = 12 - 11
x² = 1
x = √1
x = + 1 e x = - 1
*****************************************

e)
5.(x² - 1) = 4.(x² + 1)
5x² - 5 = 4x² + 4
5x² - 4x² = 4 + 5
x² = 9
x = √9
x = + 3 e x = - 3
¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨


f)
x.(x + 2) = 2x + 25
x² + 2x = 2x + 25
x² + 2x - 2x = 25
x² = 25
x = √25
x = + 5 e x = - 5

Answer 2

a)

x² - 90 = 31

x² = 31 + 90

x² = 121

x = √121

x = + 11 e x = - 11

******************************

b)

5x² + 4 = 49

5x² = 49 - 4

5x² = 45

x² = 45/5

x² = 9

x = √9

x = + 3 e x = - 3

***************************

c)

4x² - 27 = x²

4x² - x² = 27

3x² = 27

x² = 27/3

x² = 9

x = √9

x = + 3 e x = - 3

*****************************

d)

2x² + 11 = x² + 12

2x² - x² = 12 - 11

x² = 1

x = √1

x = + 1 e x = - 1

*****************************************

e)

5.(x² - 1) = 4.(x² + 1)

5x² - 5 = 4x² + 4

5x² - 4x² = 4 + 5

x² = 9

x = √9

x = + 3 e x = - 3

¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨

f)

x.(x + 2) = 2x + 25

x² + 2x = 2x + 25

x² + 2x - 2x = 25

x² = 25

x = √25

x = + 5 e x = - 5