Question

find all roots 5x^2+5x+60=0

Answer 1

Hello there, welcome to Openstudy :)
First start off by factoring out a 5

Answer 2

Basically, divide the equation by 5
x² +x +12 =0

Answer 3

what happens after x^2+x+12=0

Answer 4

Then you factor the equation. You know how to do that?

Answer 5

quadratically? i dnt know i get stuck around here

Answer 6

Hmm I don't think that factors easily. Want to try the quadratic formula?

Answer 7

ya but is there another formula?

Answer 8

no that's the only one

Answer 9

ok

Answer 10

we can solve it before it is divided by 5 or after

Answer 11

can you show me how to solve it before its divided by five

Answer 12

Sure.
The equation is
5x²+5x+60=0

a = 5 b = 5 c = 60

Answer 13

quadratic formula is
x = [-b +-square root (b² - 4*a*c)] / 2a

Answer 14

Can you fill in the formula with the a b and c values?

Answer 15

ya im doin it now

Answer 16

Okay, then I'll wait for you to finish.

Answer 17

would it be -5+-square root(-1150)

Answer 18

i think its wrong

Answer 19

Well I'll fill in the numbers hee:
a = 5 b=5 c = 60
x = [-5 +-square root(25 -4*5*60)] / 10
x= [-5 +-square root(25 -1200)] / 10
x= [-5 +-square root(-1175)] / 10

Answer 20

Seems as if you didn't have the divided by 2a in there.

Answer 21

ya i forgot to write it and can it be simplified?

Answer 22

Sure but as you can see, if you remembered the 2a then it would have been filled in correctly.

Answer 23

No, it should be square root of 1175 and not 1150

Answer 24

ya i messed up on that

Answer 25

Well we can see about simplifying this.
x= [-5 +-square root(-1175)] / 10

x = -5/10 +-square root(-47*25) / 10
x = -1/2 (+- 5* square root(-47) / 10)
x = -1/2 (+- 1/2* square root(-47))

Answer 26

it cnt be simplified anymore?

Answer 27

what would be the roots of the equation?

Answer 28

You could neaten it up by posting actual values.
x = -1/2 (+- 1/2* square root(-47))
square root of -47 is 6.8556546004 * i

so x = -1/2 + 3.4278273002 * i and
x = -1/2 - 3.4278273002 * i

Answer 29

yes - it's just that easy LOL

Answer 30

lmao thanks so the roots would be -1/2-3.4278273002

Answer 31

?

Answer 32

You forgot to add the 'i' at the end. ('i' is the square root of minus 1)

-1/2 + 3.4278273002 * i and
-1/2 - 3.4278273002 * i

Answer 33

i didnt know that why did u add the *

Answer 34

just to make the 'i' stand out a little more because it would be easy to mistake the i for a 1

Answer 35

o ok thanks a lot

Answer 36

well that's it - I trust you can use the formula a little better now.

Answer 37

def.

Answer 38

okay - see you later

Answer 39

cya