Question 49

Jambmaths question: 

A polynomial in x whose zero are –2, –1 and 3 is

Option A: 

${{x}^{3}+7x+6$

Option B: 

${x}^{3}-7x+6$

Option C: 

${x}^{3}}-7x-6$

Option D: 

${x}^{3}+7x-6$

Jamb Maths Solution: 

$\begin{align}  & \text{Since }\text{2},\text{ }\text{1 and 3 are the zeros of the function},\text{ it means} \\ & f(x)=(x+2)(x+1)(x-3) \\ & f(x)=({{x}^{2}}+3x+2)(x-3) \\ & f(x)={{x}^{3}}+3{{x}^{2}}+2x-3{{x}^{2}}-9x-6 \\ & f(x)={{x}^{3}}-7x-6 \\\end{align}$

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