Home » Aptitude » Quadratic Equation » Question
  1. If α and β are the roots of the quadratic equation ax 2 + bx + c = 0, the value of α3 + β3 is
    1. b (b2 - 3ac )
      a 3
    2. b ( 3ac - b2 )
      a 3
    3. b ( 3ac + b2 )
      a 3
    4. None of these
Correct Option: B

According to question , we can say that
Since α, β are the roots of the quadratic equation
ax 2 + bx + c = 0

∴ α + β = −
b
and αβ =
c
a
a

Now, α 3 + β 3 = ( α + β ) 3 - 3αβ( α + β )
=-
b
3- 3 x
c
x
- b
aaa
α3 + β3 =
- b 3
+
3bc
=
- b2 + 3abc
a3a2a3

Hence , α3 + β3 =
b ( 3ac - b2 )
a 3



Your comments will be displayed only after manual approval.