(i) \(x^3 + x^2 + x + 1\)
(ii) \(x^4 + x^3 + x^2 + x + 1\)
(iii) \( x^4 + 3x^3 + 3x^2 + x + 1\)
(iv) \( x^3 – x^2 – (2+\sqrt{2})x+\sqrt{2}\)
📘 Concept & Theory In this exercise, we use the Factor Theorem. ›
According to the Factor Theorem:
Here, we have to check whether \((x+1)\) is a factor of the given polynomial.
Since
Therefore, we substitute \(x=-1\) in each polynomial.
- If \(p(-1)=0\), then \((x+1)\) is a factor.
- If \(p(-1)\neq0\), then \((x+1)\) is not a factor.
🗺️ Solution Roadmap Step-by-step Plan ›
Find the zero of \((x+1)\)
- Substitute that value in each polynomial.
- Evaluate carefully step-by-step.
If the result is 0, then \((x+1)\) is a factor. Otherwise, it is not a factor.
✏️ Solution Complete Solution ›
- Given: \[\small \begin{aligned}x+1&=0\\x&=-1\end{aligned}\]
Therefore, we evaluate \(p(-1)\) for each polynomial.
- \[\small p(x)=x^{3}+x^{2}+x+1\]
- \[\small p(-1)=(-1)^{3}+(-1)^{2}+(-1)+1\]
- \[\small p(-1)=-1+1-1+1=0\]Since \(p(-1)=0\), \((x+1)\) is a factor of \(p(x)\).
✏️ Solution Complete Solution ›
- \[\small p(x)=x^{4}+x^{3}+x^{2}+x+1\]
- Substitute \(x=-1\)
- \[\small \begin{aligned} p(-1) &=(-1)^4+(-1)^3+(-1)^2+(-1)+1 \\ &=1-1+1-1+1 \\ &=(1-1)+(1-1)+1 \\ &=0+0+1 \\ &=1 \end{aligned} \]Since \(p(-1)\neq0\), \((x+1)\) is not a factor of \(p(x)\).
✏️ Solution Complete Solution ›
- \[\small p(x)=x^{4}+3x^{3}+3x^{2}+x+1\]
- Substitute \(x=-1\)
- \[\small \begin{aligned} p(-1) &=(-1)^4+3(-1)^3+3(-1)^2+(-1)+1 \\ &=1-3+3-1+1 \\ &=(1-3)+(3-1)+1 \\ &=-2+2+1 \\ &=1 \end{aligned} \]Since \(p(-1)\neq0\), \((x+1)\) is not a factor of \(p(x)\).
✏️ Solution Complete Solution ›
- \[\small p(x)=x^{3}-x^{2}-(2+\sqrt{2})x+\sqrt{2}\]
- Substitute \(x=-1\)
- \[\small \begin{aligned} p(-1) &=(-1)^3-(-1)^2-(2+\sqrt{2})(-1)+\sqrt{2} \\ &=-1-1+(2+\sqrt{2})+\sqrt{2} \\ &=-2+2+2\sqrt{2} \\ &=2\sqrt{2} \end{aligned} \]Since \(p(-1)\neq0\), \((x+1)\) is not a factor of \(p(x)\).
💡 Answer Final Answer ›
🎯 Exam Significance Exam Significance ›
- Factor Theorem is one of the most important concepts in algebra.
- It is frequently asked in school examinations and board examinations.
- This concept is also useful in competitive examinations such as NTSE, Olympiads, Polytechnic Entrance Exams, SSC and other aptitude tests.
- It helps in factorisation of higher degree polynomials quickly.
- Understanding this theorem builds a strong foundation for higher algebra.