If 1 is the zero of quadratic polynomial x^2+kx-5 , then find value of k
Answers
What is a zero?
A zero is the value of an unknown variable of a polynomial which makes the total value of polynomial zero.
For example:
x^2 + 2 x - 8
If x = 2
then: 2^2 + 2*2 - 8
= 4 + 4 - 8
=8-8
=0
Thus 2 is the zero of x^2 + 2 x - 8
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Given 1 is the zero of x^2 + k x - 5
Hence:
1^2 + k*1 - 5 =0
==> 1+k - 5 =0
==> k - 4 =0
==> k =4
The value of k is 4 for which it makes the quadratic polynomial zero.
Hope it helps you
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Given that 1 is the zero of quadratic polynomial x^2 + kx - 5, it means that the value of x is 1 and on applying the value of x( i.e. 1 ) result of the given polynomial will be 0.
Given equation : x^2 + kx - 5
Substitute the value of x in the quadratic polynomial.
⇒ ( 1 )^2 + ( 1 × k ) - 5 = 0
⇒ 1 + k - 5 = 0
⇒ k - 5 + 1 = 0
⇒ k - 4 = 0
⇒ k - 4 + 4 = 4
⇒ k = 4
Therefore the value of k satisfying the given quadratic polynomial is 4.