Solve the quadratic equation by completing the square: 2x^2 + 4x + 18 = 0 =

Question

Solve the quadratic equation by completing the square: 2x² + 4x + 18 = 0

a. x = -1 +22

b. {7, 9}

c. {-7, -9}

d. x = -1 + 2i2

Answer 1

2x^2+4x+18=0

divide all terms by 2

x^2+2x+9=0

x^2+2x    =-9

take half of 2 and square it

you get 1

add 1 to both sides

x^2+2x+1=-9+1

(x+1)^2=-8

x+1=√-8

x+1=±2√-2

x+1=±2i√2

x=-1±2i√2