Sail E0 Webinar
Question
If $${a^{\frac{1}{3}}} + {b^{\frac{1}{3}}} + {c^{\frac{1}{3}}} = 0,$$     then a relation among a, b, c is?
Options:
A .  a + b + c = 0
B .  (a + b + c)3 = 27abc
C .  a + b + c = 3abc
D .  a3 + b3 + c3 = 0
Answer: Option B
$$\eqalign{
& {\text{ }}{a^{\frac{1}{3}}} + {b^{\frac{1}{3}}} + {c^{\frac{1}{3}}} = 0 \cr
& \Rightarrow {\text{ }}{a^{\frac{1}{3}}} + {b^{\frac{1}{3}}} = - {c^{\frac{1}{3}}} \cr
& {\text{Take cube on both sides}} \cr
& \Rightarrow {\left( {{\text{ }}{a^{\frac{1}{3}}} + {b^{\frac{1}{3}}}} \right)^3} = {\left( { - {c^{\frac{1}{3}}}} \right)^3} \cr
& \Rightarrow {\text{ }}a + b + 3{a^{\frac{1}{3}}}{b^{\frac{1}{3}}}\left( {{\text{ }}{a^{\frac{1}{3}}} + {b^{\frac{1}{3}}}} \right) = - c \cr
& \Rightarrow {\text{ }}a + b + 3{a^{\frac{1}{3}}}{b^{\frac{1}{3}}}\left( {{\text{ }} - {c^{\frac{1}{3}}}} \right) = - c \cr
& \Rightarrow a + b + c = 3{a^{\frac{1}{3}}}{b^{\frac{1}{3}}}{c^{\frac{1}{3}}} \cr
& {\text{Again taking cube }} \cr
& \Rightarrow {\left( {a + b + c} \right)^3} = 27abc \cr} $$

Was this answer helpful ?
Next Question

Submit Solution

Your email address will not be published. Required fields are marked *

Latest Videos

Latest Test Papers