Can someone help me out with this..I have gotten this far and now i am stumped.?

Question

I have to solve this quadratic equation by completing the square. This is as far as I have gotten.

2x^2 +10x + 11=0
2x^2 + 10x = -11
2x^2/2 + 10x/2 = -11/2
x^2 + 5x = -11/2
x^2 + 5x + 1 = -11/2 + 1
(x + )^2 = sqrt -9/2~this is where I am stuck.
I don't know what else to do after this...can some one help me out?

Answer 1

2x^2 +10x + 11=0
2x^2 + 10x = -11
2x^2/2 + 10x/2 = -11/2
x^2 + 5x = -11/2
Up to this point, you're right.

However, you don't add 1 to each side.

You need to take the number in front of the x (not x^2), cut it in half, then square it. THAT's what you add to each side.

so...
the number in front of the x is 5
cut in half is 5/2
squared is (25 / 4)

So, you have:
x^2 + 5x + (25/4) = -11/2 + (25/4)
(x + 5/2)^2 = 3/4

Now, take the square root of both sides.
x + 5/2 = +- sqrt (3/4)
x + 5/2 = +- (sqrt 3) / 2
x = -5/2 +- (sqrt 3) / 2
x = (-5 +- sqrt 3) / 2

Answer 2

Compleing the square

2x² + 10x + 11 = 0

Divide both sides of the equation by 2

2x² / 2 + 10x / 2 + 11 / 2 = 0 / 2

x² + 5x + 11/2 = 0

Transpose 11/2

x² + 5x + 11/2 - 11/2 = 0 - 11/2

x² + 5x = - 11/2

x² + 5x +_____= - 11/2 +____

x² + 5x + 25/4 = - 11/2 + 25/4

x² + 5x + 25/4 = - 22/4 + 25/4

x² + 5x + 25/4 = 3/4

(x + 5/2)(x + 5/2) = 3/4

(x + 5/2)² = 3/4

(√x + 5/2)² = ± √3 / √4

x + 5/2 = ± √3/2

Transpose 5/2

x + 5/2 - 5/2 = - 5/2 ± √3/2

x = - 5/2 ± √3/2

x = - 5/2 ± 1.732050808 / 2

- - - - - - -

Solving for +

x = - 5/2 + 1.732050808 / 2

x = - 3.267949192 / 2

x = - 1.633974596

- - - - - - - -

Solving for -

x = - 5/2 - 1.732050898 / 2

x = - 6.732050808 / 2

x = - 3.366025404

- - - - - -s-

Answer 3

2x² + 10x + 11 = 0

to solve by completing the square

first divide thru by 2

x² + 5x + 5½ = 0

ax² + bx + c = 0

(b/2)² is your c term

5/2 = 2½

(5/2)² = 6¼

Therefore add 3/4 to both sides to complete the square

x² + 5x + 5½ + (3/4) = 3/4

x² + 5x + 6¼ = 3/4

(x + 2½)² = 3/4

Take square root of both sides

(x + 2½) = ±√(3/4)

x = -2½ ±√(3/4) or x = -2½ ±½√3
.

Answer 4

shouldn't it be
2x^2 +10x +11 =0
2x^2 +10x =-11
2x^2 +10x + 5= -11+5
2x^2 +10x +5= -6

from there I don't know which way to go but i think that that's the way to do it.

Answer 5

I would help you but I'm in the middle of surgery right now and I don't know where to make the incision. I'm waiting for somebody to answer my ? so I don't make a mistake.