Respostas

2013-08-17T22:53:27-03:00
a) 15(x+2)=0  
15x + 30 = 0
15x= - 30
x= -2

b)x(x-4)=0  
 x^{2} - 4x = 0
x (x-4)=0
x=0
x= 4

e)x²=4x  
x² - 4x = 0
x (x - 4) = 0
x=0
x= 4

f)3x²=6x  
3x² - 6x=0
3x(x - 2) = 0
x= 0
x= 2

g)3x²=15x  
3x² - 15x = 0
3x (x - 5) = 0
x=0
x = 5

h) 2x²=5x
2x² - 5x=0
x(2x - 5) = 0
x= 0
2x= 5 --> x =  \frac{5}{2}

5 3 5
c) (x+1)(2x-1)=0 d)5x(x-1)(x-2)=0
c) (x+1)(2x-1)=0 ----> 2x² + x - 1=0 -----> a= b= 1 c= -1
(delta)= 1 +8 = 9 --> [-1+ ou - rauz de 9] sobre 4
x= 1/2 x= -1
d)5x(x-1)(x-2)=0 --->