KnowledgeBoat Logo
|

Mathematics

Find the value of k, if 2x + 1 is a factor of (3k + 2)x3 + (k - 1).

Factorisation

64 Likes

Answer

2x + 1 = 0 ⇒ x = -12\dfrac{1}{2}

Since, 2x + 1 is a factor of (3k + 2)x3 + (k - 1)

∴ On substituting x = 12-\dfrac{1}{2} in (3k + 2)x3 + (k - 1), remainder = 0.

(3k+2)(12)3+(k1)=0(3k+2)8+(k1)=03k2+8k88=05k10=05k=10k=2.\Rightarrow (3k + 2)\Big(-\dfrac{1}{2}\Big)^3 + (k - 1) = 0 \\[1em] \Rightarrow \dfrac{-(3k + 2)}{8} + (k - 1) = 0 \\[1em] \Rightarrow \dfrac{-3k - 2 + 8k - 8}{8} = 0 \\[1em] \Rightarrow 5k - 10 = 0 \\[1em] \Rightarrow 5k = 10 \\[1em] \Rightarrow k = 2.

Hence, k = 2.

Answered By

32 Likes


Related Questions