x2+2x-15=0 pakai rumus abc

x2+2x-15=0
dik: a=1
b=2
c=-15
peny:
rumus abc
x= -b±√b²- 4ac /2a
x= -2 ±√(-2)² - 4.1.(-15) /2.1
x= -2 ±√4+60 /2
x= -2 ±√64 /2
x= -2 ± 8 /2
x1 = -2+8 /2
= 6/2 = 3
x2 = -2-8 /2
= -10/2 = -5