a) 6x²+0,5x=0 simplificam x
6x+0,5=0 <=> 6x=-0,5 <=>x=-0,5/6=-1/12
b) 3x²+13x-10=0 Δ=169+120=289
X1=(-13-√289)/(3·2)=(-13-17)/6=-30/6=-5
X2=(-13+√289)/(3·2)=(-13+17)/6=4/6=2/3
c) 5x(5x+2)+3=2
25x²+10x+3=2
25x²+10x+1=0
(5x+1)²=0 <=> 5x+1=0 <=> 5x=-1 <=> x=-1/5