Question

Will Give Medal!

Solve 2x2 + 12x − 14 = 0 by completing the square.

2(x + 6)2 = 26; x = −6 + square root 13, x = −6 − square root 13
2(x + 6)2 = 20; x = −6 + square root 20, x = −6 − square root 20
2(x + 3)2 = 32; x = 1, x = −7
2(x + 3)2 = 32; x = 13, x = 19

So far i got: 2x^2+12x-14=0
2(x^2+12x )-14=0
2(x^2+12x+36)-(14+72)=0
2(x+6)^2-86+86=0+86
2(x+6)^2=86
After i do this (if i did it right) im not sure what to do next...

Answer 1

um starting from beginning
2x^2+12x-14=0
factor out the common term by 2

Answer 2

Ok so 2(x^2+12x) -14=0

Answer 3

yes but put that -14 in the prathesis

Answer 4

oh ok

Answer 5

than factor it out by 2

Answer 6

what do you have now

Answer 7

What do you mean...? Is it supposed to look like this 2(x^2+12x-14)

Answer 8

no so you have 2(x^2+6x-7)=0

Answer 9

12 divideed by 2 is 6

Answer 10

-14 divided by 2 is -7

Answer 11

Oh sorry i didnt know you were supposed to do that... ok

Answer 12

do you see what im saying?

Answer 13

Yes now i do

Answer 14

its fine

Answer 15

so you have 2(x^2+6x-7)=0
now Which two numbers add up to 6 and multiply to -7?

Answer 16

none...

Answer 17

are you sure

Answer 18

yea you cant multiply anything and get 7...? i think lol

Answer 19

what is -1 plus 7

Answer 20

and what is -1 times 7

Answer 21

Oh my gosh!! i fell really dumb... ok

Answer 22

do -1 and 7 right?

Answer 23

Rewrite the expression as (x−1)(x+7)

Answer 24

so we have
2(x−1)(x+7)=0

Answer 25

Well -1 times 7 equals -7 but they dont add up to 6... and ok

Answer 26

umm -1 plus 7 is 6 lol. try doing it again

Answer 27

Ugh i am like not even paying attention today!!!! sorry i completely forgot the negative

Answer 28

it happens

Answer 29

2(x−1)(x+7)=0
When will (x−1)(x+7) equal zero?

Answer 30

um... im not completely sure..

Answer 31

ok add when will -1 = to 0

Answer 32

when you add +1 right?

Answer 33

when you add 1

Answer 34

good when will POSITIVE 7 become 0

Answer 35

@Hannahwaller5

Answer 36

Sorry i was doing something when you subtract 7

Answer 37

when you subtract 7 Great!
x=1,−7
is that one of the choice?

Answer 38

Yup thank you (:

Answer 39

so we are done! np