Question

9.
If (4 + i) is a root of the equation x² + ax + b =0, then a is
1) 8
2)-8
3)6
4)-6
​

Answer 1

Answer:

${(4 + i)}^{2} + a(4 + i) + b = 0 \\ \\ 16 - 1 + 8i + 4a + ai + b = 0 \\ \\ 15 + 4a + b + i(a + 8) = 0 \\ \\ a = - 8$