Question

Jawab jsy'^'

1.Tentukan penyelesaian persamaan kuadrat berikut dgn cara memfaktorkan :
a.x^2 + 4x - 12 = 0
b.2x^2 - 7x + 3 = 0
c.x^2 - 5x + 6 = 0
d.x^2 + 3x - 2 = 0
e.3x^2 + 8x + 4 = 0
f.2x^2 - 4x - 1 = 0

Answer 1

1a) x^2 + 4x - 12 = 0
      (x+6)(x-2) = 0
      x + 6 = 0
      x = -6
      atau
      x - 2 = 0
      x = 2

hp = { -6 , 2}

b) 2x^2 - 7x + 3 = 0
(2x - 1)(x -3) = 0
2x - 1 = 0
2x = 1
x = 1/2
atau
x - 3 = 0
x = 3

hp = {1/2  , 3}

c) x^2 - 5x + 6 = 0
(x-3)(x-2) = 0
x = 3 atau x = 2

hp = {2 , 3}

d) x^2 + 3x - 2 = 0
x^2 + 3x + 2,25 = 2 + 2,25
(x+1,5)^2 = 4,25
x+1,5 = V4,25
x = V4,25 - 1,5

e) 3x^2 + 8x + 4 = 0
(3x + 2)(x + 2) = 0
3x + 2 = 0
3x = -2
x = -2/3

atau 
x+ 2 = 0
x= -2

hp = {-2  , -2/3}

f) 2x^2 - 4x - 1 = 0
x^2 - 2x - 1/2 = 0
x^2 - 2x + 1 = 1/2 + 1
(x - 1)^2 = 3/2
x - 1 = V(3/2)
x = V(3/2) + 1

tanda V = akar