1. Tugas 1
Matematika
NAMA KELOMPOK:
I GUSTI AGUNG PUTU WIDIANA PUTRA (7)
I PUTU SUKMA ARINDRA (5)
WAHYU DWIPAYANA LIMARTA (14)
I WAYAN ADI YASA (32)
SMK N 1 TABANAN
TH. PEL. 2013/2014

2. 1. Selesaikan persamaan kuadrat dibawah ini dengan cara memfaktorkan.
a.
b.
c.
d.
e.
X2 + 5X – 50 = 0
X2 + 3X = 0
X2 – 4 = 0
2X2 + 3X + 1 = 0
3X2 + 5X – 2 = 0
2. Selesaikan persamaan kuadratberikut ini dengan melengkapkan kuadrat sempurna.
a. X2 + 5X + 4 = 0
b. 2X2 – 14X + 12 = 0
3. Selesaikan persamaan kuadrat berikut ini dengan rumus ABC.
a. X2 – 15X + 30 = 0
b. X2 + 8X – 20 = 0
c. X2 + 3X = 0
4. Tentukan P agar persamaan kuadrat (p+3) x3 + 3X – 4 = 0 → mempunyai 2 akar sama.
JAWABAN :
1.a). x2 + 5x – 50 = 0
(x - 2) (x + 25) = 0
x -2 = 0
x = -1
b). x2 + 3x = 0
(x + 1) (x + 3)
atau
x + 25 = 0
x = -25

3. x +1 = 0
atau
x = -1
x+3=0
x = -3
c). x2 – 4 = 0
(x - 2) (x + 2)
x -2 = 0
atau
x=2
x +2 = 0
x = -2
d). 2x2 +3x + 1 = 0
(2x + 1) (x + 2)
2x + 1 = 0
atau
2x = 1
2x + 2 = 0
2x = 2
x=2
e). 3x2 + 5x – 2 = 0
(3x - 2) (3x + 3)
3x – 3 = 0
atau
3x = 3
3x + 3 = 0
3x = -3
= -1
2.a). x2 + 5x + 4 = 0
x2 + 5x + (1)2 = (-4) + (1)2
x2 + 5x + 1
= -3
(x - 4)2
= -3
x + 16
= -3
x
= -3 + 16
x
= 13

4. b). 2x2 – 14x + 12 = 0
2x2 – 14x
= -12
2x2 – 14x + (1)2 = (-12) + (1)2
2x2 – 14x + 1
= -12 + 1
2x2 – 14x + 1
= -11
(2x - 14)2
= -11
2x + 196
= -11
2x
= -11 – 196
3.a). x2 – 5x + 30 = 0
a = 1, b = -15, c = 30

5. X1 =
=
X2 =
=
b). x2 + 8x – 20 = 0
a = 1, b = 8, c = -20
=
=
=
X1 =
=
X2 =
=2
=
c). x2 + 3x = 0
a = 1, b = 3, c = 0
=
=
X1 =
=
= -8

6. X2 =
=
= -3
4.) (p + 3) x3 + 3x – 4 = 0