Question

What is the answer for 2n^2-8n=-9 ?

Answer 1

2n^2-8n=9

divide by 2

2(n^2-4n) =9

add (4/2)^2 =4 to each side  completing the square

(n^2-4n+4 ) =9/2+4

(n-2)^2 = 9/2+8/2

(n-2)^2 =17/2

take the square root of each side

n-2 = +-sqrt(17/2)

add 2 to each side

n = 2+- sqrt (17/2)

Answer:2+ sqrt (17/2),2- sqrt (17/2)