2x²-5x-3=0 3x²+16x-12=0 4x²+8a-32=0

V-квадратный корень
2x²-5x-3=0

D=(-(-5))^2-4×2×(-3)=25-(-24)=25+24=49

x1=(-(-5)-V49)/2×2=(5-7)/4=-2/4=-1/2
x2=(-(-5)+V49)/2×2=(5+7)/4=12/4=3

3x²+16x-12=0
D=(-16)^2-4×3×(-12)=256-(-144)=256+144=400
x1=(-16-V400)/2×3=(-16-20)/6=-36/6=-6
x2=(-16+V400)/2×6=(-16+20)/6=4/6=2/3

4x²+8a-32=0
4x^2=32-8a
4x^2=4(8-2a)|:4
x^2=(8-2a)

x1=-V(8-2a)
x2=V(8-2a)