2k²+k-2=-1
2k²+k-1=0
k²+k/2-1/2=0
k²+k/2+(1/4)²-(1/4)²-1/2=0
(k+1/4)²-9/16=0
(k+1/4)²=9/16
k+1/4=±3/4
∴k1=-1,k2=1/2