Question

selesaikan persamaan kuadrat berikut dengan cara menggunakan rumus ABC a.6x^2-x-15=0
b.6x^2-7x=5​

Answer 1

Rumus ABC:

-b ± √b^2 - 4.a.c/2.a

1. 6x^2 - x - 15 = 0

a = 6 | b = -1 | c = -15

-(-1) ± √-1^2 - 4.6.-15/2.6

= 1 ± √1 + 360/12

= 1 ± √361/12

= 1 ± 19/12

x1 = 1 + 19/12

= 20/12

= 5/3

= 1 2/3

x2 = 1 - 19/12

= -18/12

= -3/2

= -1 1/2

2. 6x^2 - 7x = 5

6x^2 - 7x - 5 = 0

a = 6 | b = -7 | c = -5

-(-7) ± √-7^2 - 4.6.-5/2.6

= 7 ± √49 + 120/12

= 7 ± √169/12

= 7 ± 13/12

x1 = 7 + 13/12

= 20/12

= 5/3

= 1 2/3

x2 = 7 - 13/12

= -6/12

= -1/2