Solve x^2+4x=20 by completing the square

x = -2 ±2 sqrt (6)

Step-by-step explanation:

x^2+4x=20

Take the coefficient of x

4

Divide by 2

4/2 = 2

Then square it

2^2 = 4

Add this to each side

x^2+4x + 4=20+4

x^2+4x + 4=24

Take the 4/2 and rewrite as (x+2) ^2

(x+2) ^2 = 24

Take the square root of each side

sqrt ((x+2) ^2) = ± sqrt (24)

x+2 = ± sqrt (24)

Subtract 2 from each side

x+2-2 = -2 ± sqrt (24)

x = -2 ± sqrt (24)

We can simplify sqrt (24) as = sqrt (4*6) = 2sqrt (6)

x = -2 ±2 sqrt (6)