Solving this quadratic formula by completing the square and using the quadratic formula?

Question

x^+8v-9=0

Answer 1

I assume the 8v is a 8x

Completing the Square

x² + 8x - 9 = 0

x² + 8x - 9 + 9 = 0 + 9

x² + 8x = 9

x² + 8x + _____ = 9 + _____

x² + 8x + 16 = 9 + 16. . .How did I get 16. 8 is divided by 2 = 4 and 4 is squared (4)² = 16

x² + 8x + 16 = 25

The middle term is + 8x the left side of the equation

find the sum of the middle term

multiply the first term 1 times the last term 16 equals 16 and factor

factors of 16 =

1 x 16
2 x 8
4 x 4. . .<=..use there factors

+ 4 + 4 equals the sum of the middle term

insert + 4x and + 4x into the Left side of the equation

x² + 8x + 16 = 25

x ² + 4x + 4x + 16 = 25

x(x + 4) + 4(x + 4) = 25

(x + 4)(x + 4) = 25

(x + 4)² = 25

(√x + 4)² = ± √25

x + 4 = ± 5

x + 4 - 4 = - 4 ± 5

x = - 4 ± 5

- - - - - - -

Solving for +

x = - 4 + 5

x = 1

- - - - - - -

Solving for -

x = - 4 - 5

x = - 9

- - - - - - s-

Answer 2

Assume x² + 8x - 9 = 0
Factorising
(x + 9).(x - 1) = 0
x = - 9,x = 1
Completing Square
(x² + 8x + 16) - 16 - 9 = 0
(x + 4)² = 25
(x + 4) = ± 5
x = -9, x = 1
Quadratic Formula
x² + 8x - 9 = 0
x = [- 8 ± √(64 + 36)] / 2
x = [- 8 ± 10] / 2
x = - 9, x = 1

Answer 3

in fact you can see that 9 = 9*1 and 8 = 9-1 so you can write down (x+9)(x-1)

but we can complete the square
x^2 +8x -9 = (x+4)^2 - 16-9 = (x+4)^2 - 5^2
so x =5-4 =1, x = -5 -4 = -9

Answer 4

use the quadratic formula. -B (plus/minus)(square root)B(squared minus 4AC) (over) 2A...in place of A B and C put your coefficient in its place...therefore... -8plus/minus the square root of 64-36 over 2 which will give you -4.26 or -11.74....i think thats the answer...good luck...

Answer 5

Please retype the question accurately.