If alpha and beta and are the zeros of the polynomial p(x)=x^2-m(x+1)-n, then find the value of (1+Alpha) (1+beta)
Answers
Answer:
(1 + α) (1 + β) = 1 – n
Step-by-step explanation:
Given :
α and β are the zeroes of the polynomial p(x) = x² - m(x+1) - n
To find :
the value of (1 + α) (1 + β)
Solution :
To solve this question,we must know the relation between zeros and coefficients of the quadratic polynomial.
Sum of zeros = –(x coefficient)/x² coefficient
Product of zeros = constant term/x² coefficient
For the given quadratic polynomial,
First, let's get the given quadratic polynomial to the form ax² + bx + c
p(x) = x² - m(x+1) - n
p(x) = x² - mx - m - n
p(x) = x² - mx - (m + n)
- constant term = –(m + n)
- x coefficient = –m
- x² coefficient = 1
From the relation between zeros and coefficients :
α + β = -(-m)/1 = m
αβ = -(m + n)/1 = -(m + n)
Now, simplify (1 + α) (1 + β)
= (1 + α) (1 + β)
= 1(1 + β) + α(1 + β)
= 1 + β + α + αβ
= 1 + (α + β) + αβ
Substitute,
= 1 + m + [–(m + n) ]
= 1 + m – m – n
= 1 – n
x² - p ( x + 1 ) + c
⇒ x² - p x - p + c
⇒ x² - p x + ( c - p )
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Comparing with ax² + bx + c, we get :
a = 1
b = - p
c = c - p .
_______________________
Given :
( α + 1 )( β + 1 ) = 0
⇒ αβ + α + β + 1 = 0
______________________
Note that, sum of roots = - b/a
α + β = - b / a
But b = - p
a = 1
________________________
So α + β = - ( - p ) / 1 = p
Product of roots = αβ = c / a
⇒ αβ = ( c - p )
_______________________
Hence write this as :
αβ + α + β + 1 = 0
⇒ c - p + p + 1 = 0
⇒ c + 1 = 0
⇒ c = -1
______________________
Hence, the value of c is - 1.