Question

Solve each equation by completing the square:

x^2+12x+20=0

Answer 1

https://www.khanacademy.org/math/algebra/quadratics/completing_the_square/v/completing-the-square

Answer 2

video :)

Answer 3

start by getting the 20 out of there , subtract it on both sides

Answer 4

Thanks @timo86m this is really helping(:
@Jim766 so far i got that out of the video and now i have
x^2+12 = -20

Answer 5

take the 12 from 12 x and div it by 2 and then square it

Answer 6

12/2 = 6, 6^2 = ?

Answer 7

i got 36

Answer 8

THanks for medal. THe vid is great btw. Tells you how to do it and why it works

Answer 9

right now, add that to both sides

x^+12x + 36 = -20 + 36 now simplify

Answer 10

-20 + 36 = ?

Answer 11

Np @timo86m thanx for sharing it, it really helped!
@Jim766 soo wat u have to do to one side, u do to the other...it would be 16
so x^2+12x+36= 16

Answer 12

right
x^2 + 12x + 36 = 16 now the reason we chose 12/2 and then square it
is because it makes it very easy to factor

x^2 + 12x + 36 = 16

(x + 6)(x + 6) = 16

(x+ 6)^2 = 16 do you understand what I did there?

Answer 13

6 is there b/c it goes into both 12 and 36. right?

Answer 14

right 6^2 = 36 and 6+6 = 12

Answer 15

now the reason we did all this was now we have something squared on one side

(x + 6)^2 = 36 now take the square root of each side
the square root of something squared is the something before
it was squared
square root of 36 = 6 or -6 so we have

x + 6 = + or - 6 you with me on this?

Answer 16

now to finish it we solve both equations

x + 6 = 6 or x + 6 = -6 solve both of those for x

Answer 17

we have already taken the square root of 36 and got 6, don't need to do it again

x + 6 = 6
-6 -6

x = 0 now do the other one

Answer 18

So it would be:
x + 6 + 6
-6 -6
x=0

x + 6 = -6
-6 -6
x= -12

(0, -12)

Answer 19

sorry I screwed this up

it should have been (x+6)^2 = 16 , I put 36 by mistake above

so it is x +6 = 4 or x + 6 = -6
-6 -6 -6 -6
x = -2 or x = - 12

sorry for the error, hope I didn't confuse you.