Question

If one root of quadratic equation x squared minus 11 x + K is equal to zero is 9, then find the value of k ??

Answer 1

x^2-11x+k=0
a/c one root =9
let second root r
so, r+9=-(-11/1)=11 ( sum of root =-b/a)
r=2
and
9r=k/1 (multiple of root=c/a)
k=18

Answer 2

x^{2} -11x+k=0 
x=9 (given)
put the value of x in eq
9^2-11*9+k=0
81-99+k=0
-18+k=0
K=18