Question

for what value of k, x=a is a solution of equation x^2-(a+b)x + k=0?

Answer 1

${x}^{2} - (a + b)x + k = 0 \\ \\ {a}^{2} - (a + b)a + k \: = 0$
${a}^{2} - {a}^{2} - ab + k = 0$
$- ab + k = 0 \\ \\ k = ab$

Answer 2

ok thanks for the question