Question

Tentukan akar2 dgn melengkapkan kuadrat: 5x²+4x-12=0

Answer 1

5x² + 4x - 12 = 0
kedua ruas dibagi dg 5, get
x² + 4/5 x - 12/5 = 0
x² + 4/5 x = 12/5
(x + 2/5)² - 4/25 = 12/5
(x + 2/5)² = 4/25 + 60/25
(x + 2/5)² = 64/25
x + 2/5 = +- √(64/25)
x + 2/5 = +- 8/5
x = -2/5 +- 8/5
x1 = -2/5 + 8/5 = 6/5
x2 = -2/5 - 8/5 = -10/5 = - 2
akar- akarnya = {-2 , 6/5}