a, Δ= 49 +120 =169
x₁ = (7 + 13 ) /4 = 5 x ₂= ( 7 -13 ) /4 = - 6/4 = -2/3
b. Δ = 49 - 40 = 9
x₁ = ( 7 -3 ) / 4 =1 x ₂= ( 7 + 3 ) /4 = 1
c.Δ= 1 + 48 =49
x₁ = ( 1 -7 ) /12 = - 6/12 = -1/2 x ₂= ( 1 + 7) /12 = 8 /12 = 2 /3
d. Δ= 25 + 96=121
x₁ = ( 5 +11 ) /12 = 16 /12 = 4/3 x₂ = ( 5 -11 ) /12 = -6 /12 = - 1/2