Question

for what value of k, x=a is a solution of equation x2-(a+b)x+k=0

Answer 1

Given, x2 - (a+b) x + K =0

For x = a, we have

a2 - (a+b)a + K =0

⇒ a2 - a2 - ab + K =0

⇒ - ab + K =0

⇒ K = ab

Hence, for k = ab, x =a is a solution of the equation  x2 - (a+b) x + K =0.

Answer 2

here x^2-(a+b)x+k=0
=> a^2-a^2-ab+k=0
therefore k=> ab