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CBSE Class 10 Mathematics, Important Questions, Chapter 2, Polynomails, , 1 Marks Questions, 1. The graphs of y=p(x) are given to us, for some polynomials p(x). Find the number of, zeroes of p(x), in each case., , (i), , (ii), , (iii), , 1
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(iv), , (v), , (vi), , Ans. (i) The graph does not meets x-axis at all. Hence, it does not have any zero., (ii) Graph meets x-axis 1 time. It means this polynomial has 1 zero., (iii) Graph meets x-axis 3 times. Therefore, it has 3 zeroes., (iv) Graph meets x-axis 2 times. Therefore, it has 2 zeroes., , 2
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(v) Graph meets x-axis 4 times. It means it has 4 zeroes., (vi) Graph meets x-axis 3 times. It means it has 3 zeroes, , 2. Which of the following is polynomial?, (a), , (b), , (c), , (d) none of these, Ans. (d) none of these, , 3. Polynomial, , is a, , (a) linear polynomial, (b) quadratic polynomial, (c) cubic polynomial, (d) bi-quadratic polynomial, , Ans. (d) bi-quadratic polynomial, , 4. If, , and, , are zeros of, , , then the value of, , is, , (a) 5, (b) -5, (c) 8, (d) -8, , 3
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Ans. (b) -5, , 5. The sum and product of the zeros of a quadratic polynomial are 2 and -15, respectively. The quadratic polynomial is, (a), (b), (c), (d), Ans. (b), , 6. If p (x) = 2x2 โ 3x + 5, 3x + 5, then P(-1) is equal to, (a) 7, (b) 8, (c) 9, (d) 10, Ans. (d) 10, , 7. Zeros of p (x) = x2 โ 2x - 3 are, (a) 3 and 1, (b) 3 and -1, (c) -3 and -1, (d) 1 and -3, Ans. (b) 3 and -1, , 4
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8. If, , and, , are the zeros of 2x2 + 5x - 10 , then the value of, , is, , (a), , (b) 5, (c) -5, (d), , Ans. (c)-5, , 9. A quadratic polynomial, the sum and product of whose zeros are 0 and, , respectively is, (a) x2+, , (b) x2 -, , (c) x2 โ 5, (d) None of these, Ans. a) x2+, , 10. Which of the following is polynomial?, (a), , (b), , (c), , 5
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(d) none of these, Ans. (d) none of these, , 11. Polynomial, , is a, , (a) linear polynomial, (b) quadratic polynomial, (c) cubic polynomial, (d) bi-quadratic polynomial, Ans. (d) bi-quadratic polynomial, , 12. If, , and, , are zeros of, , , then the value of, , is, , (a) 5, (b) -5, (c) 8, (d) -8, Ans. (b) -5, , 13. The sum and product of the zeros of a quadratic polynomial are 2 and -15, respectively. The quadratic polynomial is, (a), (b), (c), (d), Ans. (b), , 6
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CBSE Class 10 Mathematics, Important Questions, Chapter 2, Polynomails, , 2 Marks Questions, 1. Find the quadratic polynomial where sum and product of the zeros are a and, , ., , Ans. Polynomial, , 2. If, , are the zeros of the quadratic polynomial, , and, , value of, , find the, , +, , Ans., , 7
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3. If the square of the difference of the zeros of the quadratic polynomial f(x) = x2+ px, +45 is equal to 144, find the value of p., , Ans., , 4. Divide, , by, , Ans., , 5. Find the value of โkโ such that the quadratic polynomial x2 - (k + 6) x + 2 (2k +1) has, sum of the zeros is half of their product., , 8
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Ans. Sum of the zeros =, , 6. If, , that (, , and, , +1) (, , are the zeros of the quadratic polynomial f(x) = x2 โ p (x + 1) โ c, show, , +1) = 1 โ c., , Ans., , 7. If the sum of the zeros of the quadratic polynomial f (t) = kt2 + 2t + 3k is equal to their, product, find the value of โkโ., Ans., , 9
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8. Divide (x4 - 5x + 6) by (2 โ x2)., Ans., , Quotient =, , Remainder = -5x + 10, , 9. Find the zeros of the polynomial p(x) = 4, , x2 + 5x โ 2, , and verify the relationship, , between the zeros and its coefficients., Ans., , 10
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10. Find the value of โkโ so that the zeros of the quadratic polynomial 3x2 โ kx + 14 are in, the ratio 7:6., Ans. Let the zeros are 7p and 6p., , 11. If one zero of the quadratic polynomial f(x) = 4x2 โ 8kx โ 9 is negative of the other,, find the value of โkโ., Ans., , 11
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CBSE Class 10 Mathematics, Important Questions, Chapter 2, Polynomails, , 3 Marks Questions, 1. Apply division algorithm to find the quotient q (x) and remainder r (x) an dividing f, (x) by g (x), where, Ans., , 2. If two zeros of the polynomial, , are, , , find the, , other zeros., Ans. Two zeros are, , 13
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Now,, , 3. What must be subtracted from the polynomial, that the resulting polynomial is exactly divisible by, , so, ?, , Ans., , We must be subtract (2x โ 3) to become a factor., , 14
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4. What must be added to, divisible by, , so that it may be exactly, , ?, , Ans., , So we must be added, , 5. Find all the zeros of the polynomial f (x) = 2x4 โ 3x3 - 3x2 +6x โ 2, if being given that, two of its zeros are, , and -, , ., , Ans., , 15
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6. On dividing x3 โ 3x2 + x + 2 by a polynomial g (x) the quotient and the remainder were, (x โ 2) and -2x + 4 respectively, find g (x)., Ans., , 16
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7. Find all zeros of f(x) = 2x3 - 7x2 + 3x + 6 if its two zeros are -, , and, , ., , Ans., , 17
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8. Obtain all zeros of the polynomial f (x) = 2x4 + x3 - 14x2 โ 19x โ 6, if two of its zeros are, -2 and -1., Ans., , 18
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11. Find the value of โkโ for which the polynomial x4 + 10x3 + 25x2 + 15x + k is exactly, divisible by (x + 7)., Ans., , 12. If, , and, , are the zeros of the polynomial f (x) = x2 + px + q, find polynomial, , 20
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whose zeros are (, , +, , )2 and (, , -, , )2., , Ans., , 21
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CBSE Class 10 Mathematics, Important Questions, Chapter 2, Polynomails, , 4 Marks Questions, 1. Divide the polynomial p(x) by the polynomial g(x) and find the quotient and, remainder in each of the following., (i) p(x) = x3 โ 3x2 + 5x โ 3, g(x) = x2 โ 2, (ii) p(x) = x4 โ 3x2 + 4x + 5, g(x) = x2 โ x + 1, (iii) p(x) = x4 โ 5x + 6, g(x) = 2 โ x2, Ans. (i), , Therefore, quotient =x โ 3and Remainder =7x โ 9, (ii), , 22
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(ii), , Remainder = 0, Hence first polynomial is a factor of second polynomial., (iii), , Remainder โ 0, Hence first polynomial is not factor of second polynomial., , 3. Obtain all other zeroes of (3x4+6x3โ2x2โ10xโ5), if two of its zeroes are, , Ans. Two zeroes of (3x4+6x3โ2x2โ10xโ5) are, , and, , and, , ., , which means that, , 24
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p(x)=g(x).q(x)+r(x), โx3โ3x2+x+2 = g(x).(xโ2)โ2x+4, โx3โ3x2+x+2+2xโ4=g(x).(xโ2), โx3โ3x2+3xโ2=g(x).(xโ2), โg(x)=, , So, Dividing (x3โ3x2+3xโ2) by (xโ2), we get, , Therefore, we have g(x)=, , =x2โx+1, , 5. Give examples of polynomials p(x), g(x), q(x) and r(x), which satisfy the division, algorithm and, (i) deg p(x)=deg q(x), (ii) deg q(x)=deg r(x), (iii) deg r(x)=0, Ans. (i) Let p(x)=3x2+3x+6, g(x)=3, , 26
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So, we can see in this example that deg p(x)=deg q(x)=2, (ii) Let p(x)=x3+5 and g(x)=x2โ1, , We can see in this example that deg q(x)=deg r(x) =1, (iii) Let p(x)=x2+5xโ3, g(x) =x+3, , We can see in this example that deg r(x)=0, , 6. Find the zeroes of the following quadratic polynomials and verify the relationship, , 27
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between the zeros and the coefficients., (i) x 2 โ2xโ8, (ii) 4s2โ4s+1, (iii) 6x2โ3โ7x, (iv) 4u2+8u, (v) t 2 โ15, (vi) 3x2โxโ4, Ans. (i) x2โ2xโ8, Comparing given polynomial with general form ax2+bx+c,, We get a=1, b=-2 and c=-8, We have, x2โ2xโ8, =x2โ4x+2xโ8, =x(xโ4)+2(xโ4)=(xโ4)(x+2), Equating this equal to 0 will find values of 2 zeroes of this polynomial., (xโ4)(x+2)=0, โ x=4,โ2 are two zeroes., Sum of zeroes =4 โ 2=2 =, , =, , Product of zeroes =4รโ2=โ8 =, , (ii) 4s2โ4s+1, , 28
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โ x=, , Therefore, two zeroes of this polynomial are, , Sum of zeroes=, , Product of Zeroes =, , (iv) 4u2+8u, Here, a=4, b=8 and c=0, 4u2+8u = 4u(u+2), Equating this equal to 0 will find values of 2 zeroes of this polynomial., โ 4u(u+2)=0, โ u=0,โ2, Therefore, two zeroes of this polynomial are 0,โ2, Sum of zeroes =0โ2=โ2 =, , =, , Product of Zeroes =0รโ2=0 =, , (v) t2โ15, Here, a=1, b=0 and c=-15, We have, t2โ15, โ t2=15, , 30
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โ t=, , Therefore, two zeroes of this polynomial are, , Sum of zeroes=, , Product of Zeroes =, , (vi) 3x2โxโ4, Here, a=3, b=-1 and c=-4, We have, 3x2โxโ4=3x2โ4x+3xโ4, =x(3xโ4)+1(3xโ4)=(3xโ4)(x+1), Equating this equal to 0 will find values of 2 zeroes of this polynomial., โ (3xโ4)(x+1)=0, โ x=, , Therefore, two zeroes of this polynomial are, , Sum of zeroes=, , Product of Zeroes =, , 7. Find a quadratic polynomial each with the given numbers as the sum and product of, , 31
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its zeroes respectively., (i), , , โ1, , (ii), , ,13, , (iii) 0,, , (iv) 1, 1, (v), , (vi) 4, 1, Ans. (i), , , โ1, , Let quadratic polynomial be ax2+bx+c, Let ฮฑ and ฮฒ are two zeroes of above quadratic polynomial., ฮฑ+ฮฒ =, , ฮฑร ฮฒ=-1, , =, , =, , Quadratic polynomial which satisfies above conditions= 4x2โxโ4, (ii), , Let quadratic polynomial be ax2+bx+c, Let ฮฑ and ฮฒ be two zeros of above quadratic polynomial., , 32
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Quadratic polynomial which satisfies above conditions= x2โx+1, (v), , Let quadratic polynomial be ax2+bx+c, Let ฮฑ and ฮฒ be two zeros of above quadratic polynomial., ฮฑ+ฮฒ=, , ฮฑร ฮฒ=, , =, , =, , Quadratic polynomial which satisfies above conditions= 4x2+x+1, (vi) 4, 1, Let quadratic polynomial be ax2+bx+c, Let ฮฑ and ฮฒ be two zeros of above quadratic polynomial., ฮฑ+ฮฒ=4, , ฮฑร ฮฒ= 1, , =, , =, , Quadratic polynomial which satisfies above conditions= x2โ4x+1, , 8. Verify that the numbers given alongside of the cubic polynomials below are their, , 34
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zeroes. Also verify the relationship between the zeroes and the coefficients in each, case:, (i), , (ii), , Ans. (i) Comparing the given polynomial with, , , we get, , and, , =, , =, , =0, , =, , =0, , =, =, , =0, and, , Now,, , are the zeroes of, , =, , And, , 35
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=, , =, , And, , =, , =, , (ii) Comparing the given polynomial with, , , we get, , and, , =, , =0, , =, , =0, and, , are the zeroes of, , Now,, , =, , And, , =, , And, , =, , =, , =, , 9. Find a cubic polynomial with the sum of the product of its zeroes taken two at a time, and the product of its zeroes are, Ans. Let the cubic polynomial be, , respectively., and its zeroes be, , and, , 36
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Then, , =2=, , and, , =, , And, , =, , Here,, , and, , Hence, cubic polynomial will be, , 10. If the zeroes of the polynomial, Ans. Since, , are, , find, , and, , are the zeroes of the polynomial, , =, , And, =, , 37
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Hence, , and, , ., , 11. If the two zeroes of the polynomial, , are, , find, , other zeroes., Ans. Since, , are two zeroes of the polynomial, , Let, , Squaring both sides,, , Now we divide, , by, , to obtain other zeroes., , =, =, =, , 38
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=, and, , are the other factors of, , and 7 are other zeroes of the given polynomial., , 12. If the polynomial, , is divided by another polynomial, , the remainder comes out to be, Ans. Let us divide, , find, by, , and, ., , Remainder =, On comparing this remainder with given remainder, i.e., , And, , 39