Respuesta :

Answer:

option b is the correct answer.

Explanation is beloe

Step-by-step explanation:

x²+y²=9

xy=8

x+y=?

Now,

(x+y)²=x²+2×x×y+y²

(x+y)²=x²+2xy+y²

(x+y)²=x²+y²+2xy

(x+y)²=9+2×8

(x+y)²=9+16

(x+y)²=25

(x+y)²=5²

x+y=±5

I hope it helped U

stay safe stay happy

Step-by-step explanation:

[tex]we \: have \: {(x + y)}^{2} = {x}^{2} + {y}^{2} + 2xy \\ here \: {x}^{2} + {y}^{2} = 9 \\ xy = 8 \\ then {(x + y)}^{2} = 9 + 2 \times 8 \\ {(x + y)}^{2} = 9 + 16 = 25 \\ {(x + y)}^{2} = 25 \\ x + y = \sqrt{25} = +/-5 \\ thank \: you[/tex]