Rewrite the function by completing the square r^2+18x+80=0

x = - 10, - 8

Step-by-step explanation:

x^2+18x+80=0

Subtract 80 from each side

x^2+18x=-80

Take the coefficient of x

18

Divide by 2

18/2 = 9

Square it

9^2 = 81

Add 81 to each side

x^2+18x + 81=-80+81

(x + 9) ^2 = 1

Take the square root of each side

sqrt ((x + 9) ^2) = ±sqrt (1)

x+9 = ±1

Subtract 9 from each side

x+9-9 = - 9 ±1

x = - 9+1 x = - 9-1

x = - 8 x = - 10