Resposta:
3)A 4)C
Explicação passo-a-passo:
3)Δ=b²-4ac=(-4)²-4*1*(-5)=16+20=36; x=-b±√Δ/2a=-(-4)±√36/2*1=(4±6)/2; x1=4+6/2=10/2=5; x2=4-6/2=-2/2=-1; 4)8x²-24x+18=0; 4x-12x+9=0; Δ=(-12)²-4*4*9=144-144=0; x=-(-12)±0/2*4=12/8=3/2
