Question

Pls answer with method.....

Answer 1

sum of roots = 0
- b/a = 0
- (k-1) / 9 = 0
k = 1

Answer 2

What is additive inverse ?

Additive inverse is a number to which if you add another number gives 0 .

Suppose x is an additive inverse of y .

Then x + y = 0.

This means y = - x

Additive inverse is just the number in negative : )

Given 9 x^2 + ( k - 1 ) x - 1 = 0

Roots are additive inverse .

So the sum of the roots will be 0 .

Also :

Sum of roots in quadratic equation = - b / a

Comparing 9 x^2 + ( k - 1 ) x - 1 = 0 with

a x^2 + b x + c = 0

a = 9

b = ( k - 1 )

c = -1

So sum of roots = - b / a = 0

= > - b = 0

= > b = 0

Hence k - 1 = 0

= > k = 1

ANSWER:

The value of k is 1