Question

Determine o conjunto de soluçao de cada expresao
b)5x²-3x=0
c)7x²-x=0
d)-15x²-5x=0
e)x²+x=0
f)x²+16=0
g)x²-64=0
h)(-x-5)²=25-9x
i)2x(x+1)-x(x+5)=3(12-x)

Answer 1

b) 5x² - 3x = 0

x.(5x - 3) = 0

x = 0 

5x - 3 = 0

5x = + 3

x = 3/5

S{0 ; 3/5}


 
c)7x²-x=0

x.(7x - 1) = 0

x = 0

7x - 1 = 0

7x = + 1

x = 1/7

S:{0 ; 1/7}



d) -15x²-5x=0  : (5)

- 3x² - x = 0  .(-1)

3x² + x = 0

x.(3x + 1) = 0

x = 0

3x + 1 = 0

3x = - 1

x = - 1/3

S{0 ; - 1/3}



e) x²+x=0

x.(x + 1) = 0

x = 0

x + 1 = 0

x = - 1

S{- 1 ; 0}



f) x²+16=0

x² = - 16

x = ±  √-16   ⇒  ∉ R


g) x²- 64=0

x² = + 64

x = ± √64

x = ± 8

S{- 8 ; + 8}



h) (-x-5)²=25-9x

(-x - 5).(-x - 5) = 25 - 9x

+ x² + 5x + 5x  + 25 = 25 + 9x

x² + 10x - 9x + 25 - 25 = 0     cancela o +25 - 25

x² + x = 0

x.(x + 1) = 0

x = 0

x + 1 = 0

x = - 1

S{- 1 ; 0}



i) 2x(x+1)-x(x+5)=3(12-x)

2x² + 2x - x² - 5x = 36 - 3x

2x² - x² + 2x + 3x - 5x - 36 = 0

x² + 5x - 5x - 36 = 0     cancela + 5x - 5x

x² - 36 = 0

x² = + 36

x = ± √36

x = ± 6

S{ - 6 ; + 6}