Question

Solve the quadratic by completing the square.

Answer 1

It's the second choice: x = (-4 + 5i) / 2.

Explanation:

4x^2 + 16x + 49 = 8

4x^2 + 16x = 8 - 49

4 (x^2 + 4x) = -41

x^2 + 4x = -41/4

(x + 2)^2 - 4 = -41/4

(x + 2)^2 = -41/4 + 16/4

(x + 2)^2 = -25/4

x + 2 = 5i / 2

x = (-4 + 5i) / 2.

Answer 2

x1=(-4+5i)/2

x2=(-4-5i)/2

Explanation:

4x^2 +16x+49=8

4x^2+16x+49-8=0

4x^2 +16x+41=0

a=4, b=16, c=41

x1=(-b+sqrt(b^2-4ac))/2a

x2=(-b-sqrt(b^2-4ac))/2a

x1=(-16+sqrt(16^2-4*4*41))/2*4

x1=(-16+sqrt(256-656))/8

x1=(-16+sqrt(-400))/8

x1=(-16+20i)/8

x1=(-4+5i)/2

x2=(-4-5i)/2