algebra 1

Couple of ways to solve this for 'x'    COmplete the square or Quadratic Formula

Completing the square:

x^2 + 4x - 16 = 0     Add 16 to both sides of the equation, then take 1/2 of the midle term,(4) square it and add it to both sides

x^2 + 4x + 4 = 16 + 4

(x+2)^2   = 20                  Now take the sq rt of both sides

x+2 =  + - sqrt (20)              Now subtract 2 from both sides

x =  -2  +- sqrt(20)

Solve for x:
x^2+4 x-16=0

 

Add 16 to both sides:
x^2+4 x=16

 

Add 4 to both sides:
x^2+4 x+4=20

 

Write the left hand side as a square:
(x+2)^2=20

 

Take the square root of both sides:
x+2=2 sqrt(5) or x+2=-2 sqrt(5)

 

Subtract 2 from both sides:
x=2 sqrt(5)-2 or x+2=-2 sqrt(5)

 

Subtract 2 from both sides:
Answer: |  x=2 sqrt(5)-2      or      x=-2-2 sqrt(5)