A polynomialp(x) in one variable x is an algebraic expression in x of
the form
p(x) = anxn + an–1xn – 1 + . . . + a2x2 + a1x + a0,
where a
0, a1, a2, . . ., an are constants and an ≠ 0.
a
0, a1, a2, . . ., an are respectively the coefficients of x0, x, x2, . . ., xn,
and n is called the degree
of the polynomial. Each ofanxn, an–1 xn–1, ..., a0, with an≠ 0, is
called a term of the polynomial
p(x).
The degree of a polynomial is the highest power
of it terms
ex- 2x2+6x+12 (degree = 2)
Polynomials of degrees
1- linear polynomial
2- quadratic polynomial
3- cubic polynomial
A zero or root of a polynomial is a number that,
when plugged in for the variable, makes the
function equal to zero . To fide the zero of the
polynomial just make factor of it by splitting the
middle term
Ex- 12x2 – 7x + 1
Here p+q = - 7 , pq = 12
= 12 × 1 = 12
Therefore p + q = – 7 = – 4 – 3
and pq = 12 = (– 4)(–3)
Therefore
12x2 – 7x + 1= 12x2+(– 4 – 3)x+1
= 12x2 – 4x – 3x +1
=4x(3x-1)-1(3x-1)
=(4x-1)(3x-1)
(4x-1)(3x-1)
Therefore
X= 1/4
X= 1/3
Therefore zeros are are 1/4 1/3
It means the polynomial f(x) is equals to
zero when x is 1/3 1/4
Ex= x3 + 13x2+ 32x + 20
here we hat to split two middle terms 13x2 ,32x
We can write 13x2 =x2 + 12x2
32x =12x + 20x
therefore x3 + 13x2+ 32x + 20= x3+x2+12x2 +12x+20x+20
=x2(x+1) 12x(x+1) 20(x+1)
=(x+1)(x2 +12x+20)
Now we have two factors (x+1)(x2 +12x+20) but f(x) is cubic
polynomial ,so it has three factor
Now we make factors of (x2 +12x+20)
(x2 +12x+20)= x2 +2x+10x+20
= x(x+2)10(x+2)
= (x+10)(x+2)
= (x+1) (x+10)(x+2) are factor of f(x)
Therefore
X=-1,-10,-2
It means the polynomial f(x) is equals to zero when x is 1,-10,-2
In general, ifα and β are the zeroes of the quadratic polynomialp(x) =
ax2+ bx + c,
a ≠ 0, then you know that x – α and x – β are the factors of p(x).
Therefore,
ax2 + bx + c = k(x – α) (x – β), where k is a constant
= k[x2 – (α + β)x + α β]
= kx2 – k(α + β)x + k α β
Comparing the coefficients of x2, x and constant terms on both the
sides, we get
a = k, b = – k(α + β) and c = kαβ.
This gives α + β =-b/a
αβ =c/a
EX-Find the zeroes of the polynomial x2 – 3 and verify the
relationship between the zeroes and the coefficients.
Recall the identity a2 – b2 = (a – b)(a + b). Using it, we can write:
x2 – 3 = ( x+√3 )(x− √3)
So, the value of x2 – 3 is zero when x = 3 or x = – 3⋅
Therefore, the zeroes of x2 –3 are x+ √3 and x-√3
Therefore
X= -√3=α
X=+√3=β
Now compare the f(x) to ax2 + bx + c
a=1 , b=0 , c=-3
Now we know that
α + β =-b/a
so √3+(-√3)=-0/1
0=0 (hence proved)
αβ =c/a
So √3 X (-√3) = -3/1
-3=-3(hence proved)

Polynomials

  • 2.
    A polynomialp(x) inone variable x is an algebraic expression in x of the form p(x) = anxn + an–1xn – 1 + . . . + a2x2 + a1x + a0, where a 0, a1, a2, . . ., an are constants and an ≠ 0. a 0, a1, a2, . . ., an are respectively the coefficients of x0, x, x2, . . ., xn, and n is called the degree of the polynomial. Each ofanxn, an–1 xn–1, ..., a0, with an≠ 0, is called a term of the polynomial p(x).
  • 3.
    The degree ofa polynomial is the highest power of it terms ex- 2x2+6x+12 (degree = 2) Polynomials of degrees 1- linear polynomial 2- quadratic polynomial 3- cubic polynomial
  • 4.
    A zero orroot of a polynomial is a number that, when plugged in for the variable, makes the function equal to zero . To fide the zero of the polynomial just make factor of it by splitting the middle term
  • 5.
    Ex- 12x2 –7x + 1 Here p+q = - 7 , pq = 12 = 12 × 1 = 12 Therefore p + q = – 7 = – 4 – 3 and pq = 12 = (– 4)(–3) Therefore 12x2 – 7x + 1= 12x2+(– 4 – 3)x+1 = 12x2 – 4x – 3x +1 =4x(3x-1)-1(3x-1) =(4x-1)(3x-1)
  • 6.
    (4x-1)(3x-1) Therefore X= 1/4 X= 1/3 Thereforezeros are are 1/4 1/3 It means the polynomial f(x) is equals to zero when x is 1/3 1/4
  • 7.
    Ex= x3 +13x2+ 32x + 20 here we hat to split two middle terms 13x2 ,32x We can write 13x2 =x2 + 12x2 32x =12x + 20x therefore x3 + 13x2+ 32x + 20= x3+x2+12x2 +12x+20x+20 =x2(x+1) 12x(x+1) 20(x+1) =(x+1)(x2 +12x+20)
  • 8.
    Now we havetwo factors (x+1)(x2 +12x+20) but f(x) is cubic polynomial ,so it has three factor Now we make factors of (x2 +12x+20) (x2 +12x+20)= x2 +2x+10x+20 = x(x+2)10(x+2) = (x+10)(x+2) = (x+1) (x+10)(x+2) are factor of f(x) Therefore X=-1,-10,-2 It means the polynomial f(x) is equals to zero when x is 1,-10,-2
  • 9.
    In general, ifαand β are the zeroes of the quadratic polynomialp(x) = ax2+ bx + c, a ≠ 0, then you know that x – α and x – β are the factors of p(x). Therefore, ax2 + bx + c = k(x – α) (x – β), where k is a constant = k[x2 – (α + β)x + α β] = kx2 – k(α + β)x + k α β Comparing the coefficients of x2, x and constant terms on both the sides, we get a = k, b = – k(α + β) and c = kαβ. This gives α + β =-b/a αβ =c/a
  • 10.
    EX-Find the zeroesof the polynomial x2 – 3 and verify the relationship between the zeroes and the coefficients. Recall the identity a2 – b2 = (a – b)(a + b). Using it, we can write: x2 – 3 = ( x+√3 )(x− √3) So, the value of x2 – 3 is zero when x = 3 or x = – 3⋅ Therefore, the zeroes of x2 –3 are x+ √3 and x-√3 Therefore X= -√3=α X=+√3=β
  • 11.
    Now compare thef(x) to ax2 + bx + c a=1 , b=0 , c=-3 Now we know that α + β =-b/a so √3+(-√3)=-0/1 0=0 (hence proved) αβ =c/a So √3 X (-√3) = -3/1 -3=-3(hence proved)