Question

Solve this quadratic equation by completing the square. x^2+4x=15

Answer 1

Answer:

x =  -2  ±sqrt( 19)

Step-by-step explanation:

x^2 + 4x = 15

Take the coefficient of x

4

Divide by 2

4/2 =2

Square it

2^2 = 4

Add it to each side

x^2 + 4x+4 = 15+4

(x+2)^2 = 19

Take the square root of each side

sqrt( (x+2)^2) =±sqrt( 19)

x+2 =  ±sqrt( 19)

Subtract 2 from each side

x+2-2 = -2  ±sqrt( 19)

x =  -2  ±sqrt( 19)