Find the best tutors and institutes for Class 10 Tuition
Q3(iv):
Find the value of $k$, if $x – 1$ is a factor of $p(x)$ in each of the following cases:
(iv) $p(x) = kx^2 – 3x + k$
Solution :
Initial Setup & Theoretical Foundation
We are given the polynomial function $p(x)$ and a linear binomial $g(x)$ which is stated to be a factor of $p(x)$:
- Dividend Polynomial: $p(x) = kx^2 - 3x + k$
- Linear Factor: $g(x) = x - 1$
[Per the Factor Theorem, a polynomial $p(x)$ has a factor $(x - c)$ if and only if the polynomial evaluates to zero at $x = c$, meaning $p(c) = 0$. This is a direct corollary of the Remainder Theorem, where a remainder of zero indicates perfect divisibility.]
Step 1: Determining the Root of the Linear Factor
To apply the Factor Theorem, we must first find the zero of the linear divisor $g(x)$. We do this by setting the factor equal to zero and solving for $x$:
$x - 1 = 0$
$x = 1$
[This establishes that $c = 1$. Therefore, if $x - 1$ is a factor of $p(x)$, evaluating $p(x)$ at $x = 1$ must yield exactly $0$.]
Step 2: Applying the Factor Theorem
We substitute $x = 1$ into the polynomial $p(x)$ and set the entire expression equal to zero:
$p(1) = k(1)^2 - 3(1) + k = 0$
Step 3: Algebraic Evaluation for $k$
Now, we simplify the equation to isolate and solve for the unknown constant $k$:
- Evaluate the exponent and multiplication: $k(1) - 3 + k = 0$
- Combine like terms ($k + k$): $2k - 3 = 0$
- Add $3$ to both sides of the equation: $2k = 3$
- Divide by $2$: $k = \frac{3}{2}$
Graphical Verification (Visualizing the Polynomial)
By substituting $k = \frac{3}{2}$ back into the original equation, the polynomial becomes $p(x) = \frac{3}{2}x^2 - 3x + \frac{3}{2}$. Factoring out $\frac{3}{2}$ yields $p(x) = \frac{3}{2}(x^2 - 2x + 1) = \frac{3}{2}(x - 1)^2$. This reveals that $x = 1$ is a repeated root, meaning the parabola's vertex rests exactly on the x-axis at $x = 1$.
Final Solution: The value of $k$ for which $x - 1$ is a factor of $p(x) = kx^2 - 3x + k$ is $k = \frac{3}{2}$.
More Questions from Class 9 Mathematics Polynomials EXERCISE 2.3
- Q1(i): Determine which of the following polynomials has $(x + 1)$ a factor : (i) $x^3 + x^2 + x + 1$
- Q1(ii): Determine which of the following polynomials has $(x + 1)$ a factor : (ii) $x^4 + x^3 + x^2 + x + 1$
- Q1(iii): Determine which of the following polynomials has $(x + 1)$ a factor : (iii) $x^4 + 3x^3 + 3x^2 + x + 1$
- Q1(iv): Determine which of the following polynomials has $(x + 1)$ a factor : (iv) $x^3 – x^2 – (2 + \sqrt{2})x + \sqrt{2}$
- Q2(i): Use the Factor Theorem to determine whether $g(x)$ is a factor of $p(x)$ in each of the following cases: (i) $p(x) = 2x^3 + x^2 – 2x – 1, g(x) = x + 1$
- Q2(ii): Use the Factor Theorem to determine whether $g(x)$ is a factor of $p(x)$ in each of the following cases: (ii) $p(x) = x^3 + 3x^2 + 3x + 1, g(x) = x + 2$
- Q2(iii): Use the Factor Theorem to determine whether $g(x)$ is a factor of $p(x)$ in each of the following cases: (iii) $p(x) = x^3 – 4x^2 + x + 6, g(x) = x – 3$
- Q3(i): Find the value of $k$, if $x – 1$ is a factor of $p(x)$ in each of the following cases: (i) $p(x) = x^2 + x + k$
- Q3(ii): Find the value of $k$, if $x – 1$ is a factor of $p(x)$ in each of the following cases: (ii) $p(x) = 2x^2 + kx + \sqrt{2}$
- Q3(iii): Find the value of $k$, if $x – 1$ is a factor of $p(x)$ in each of the following cases: (iii) $p(x) = kx^2 – \sqrt{2}x + 1$
- Q4(i): Factorise : (i) $12x^2 – 7x + 1$
- Q4(ii): Factorise : (ii) $2x^2 + 7x + 3$
- Q4(iii): Factorise : (iii) $6x^2 + 5x – 6$
- Q4(iv): Factorise : (iv) $3x^2 – x – 4$
- Q5(i): Factorise : (i) $x^3 – 2x^2 – x + 2$
- Q5(ii): Factorise : (ii) $x^3 – 3x^2 – 9x – 5$
- Q5(iii): Factorise : (iii) $x^3 + 13x^2 + 32x + 20$
- Q5(iv): Factorise : (iv) $2y^3 + y^2 – 2y – 1$
CBSE Solutions for Class 9 Mathematics Polynomials
Chapters in CBSE - Class 9 Mathematics
Top Tutors who teach Polynomials
I am a professional french tutor with 5 years of experience in teaching languages. I can teach efficiently to all school students as well as adults, for delf-dalf, migration, jobs and other purposes. Over my years teaching, I have been know to be amiable amd flexible according to my students' needs. I always schedule a free demo session for the student to get comfortable with me my teaching techniques and vice versa. The classes I conduct are via offline and online mode both, as preferred.
Being a professional tutor , I have an experience of more than 9 years , my students are my strength , i always dedicated for my students.
A+ tutor for Maths and Science class 10. Highly recommended, very humble and polite. You should go for him without doubts.
I am a freelance tutor at present. I taught in a coaching centre Vidyanext for students of CBSE & ICSE of classes IX & X for two years. I have teaching children of classes IX & X since last ten years online and also at my home. You can check my profile for the same. My teaching methodology would be to clear the concepts of the child, make the child practice and then test him on his concepts by giving worksheets. This methodology worked well even with dull students and almost all my students have scored and are scoring well in the board exams.
Swathi was very professional and knowledgeable. I highly recommend her for International students and domestic as well. I would definitely prefer her for my future Mathematical learning. Thanks
I am an experienced Spoken English and Class VI-X subject tutor with two years of experience in teaching. Currently, I am pursuing my bachelor's degree in BA from Magadh University. I can teach students who are in State, International Baccalaureate, CBSE and ICSE Board. My students have improved a lot through my teaching, and I've received five reviews till now with 100% positive feedback. I always try to understand my students and help them overcome their fear of failure in specific subjects like math and science.
5 years experience in teaching in math and science
Find more Tutor for Polynomials in your City
- Bangalore Mathematics Tutors
- Delhi Mathematics Tutors
- Chennai Mathematics Tutors
- Gurgaon Mathematics Tutors
- Noida Mathematics Tutors
- Hyderabad Mathematics Tutors
- Mumbai Mathematics Tutors
- Chandigarh Mathematics Tutors
- Pune Mathematics Tutors
- Ghaziabad Mathematics Tutors
- Jaipur Mathematics Tutors
- Surat Mathematics Tutors
Download free CBSE - Class 9 Mathematics Polynomials EXERCISE 2.3 worksheets
Download Now