a) 6x²+0,5x=0
0,5x(3x+1)=0
0,5x=0 sau 3x+1=0
x=0 sau x=-⅓
S={0;-⅓}
b) 3x²+13x-10=0
a=3
b=13
c=-10
∆= b²-4ac
∆= 13²-4*3*(-10)=169+120=289
x1=(-b+√∆)/2a=(-13+17)/2*3=4/6=⅔
x2=(-b-√∆)/2a=(-13-17)/2*3=-30/6=-5
S={-5;⅔}
c) 5x(5x+2)+3=2
5x²+10x+3-2=0
5x²+10x+1=0
a=5
b=10
c=1
∆=b²-4ac
∆=10²-4*5*1=100-20=80
x1=(-b-√∆)/2a=(-10+4√5)/2*5=(-10+4√5)/10=(-5+2√5)/5
x2=(-b-√∆)/2a=(-10-4√5)/10=(-5-2√5)/5
S={ (-10+2√5)/5; (-10-2√5)/5}
