Question

Which of the following is a solution of 9x^2-5x = -3? (Quadratic formula)

Answer 1

\(9x^2-5x +3=0 \)
Compare this quadratic equation with \(ax^2+bx+c=0\)
find \[a=...?\\b=...?\\c=...?\\\] \[ \\ \sqrt{b^2-4ac}=...?\]
then the two roots of x are:
\(\huge{x_{1,2}=\frac{-b \pm \sqrt{b^2-4ac}}{2a}}\)

Answer 2

wait that didn't help??

Answer 3

i obviously know that

Answer 4

but the answers have "i" in them so I'm confused

Answer 5

@hartnn there's no point in just typing the quadratic formula. if i know i have to use it for the problem, i can just look it up. if ur not gonna help, then..

Answer 6

I mean, like, i just don't need info I already have

Answer 7

yes, first tell me what you get for b^2-4ac ?

Answer 8

the choices are up there^^

Answer 9

could you find a,b,c ?

Answer 10

hold on

Answer 11

yeah ok, so a=9, b= -5, c= -3

Answer 12

and what do you mean "the two roots of x"

Answer 13

why does it say x 1,2 in front of the formula

Answer 14

that there are 2 solutions for x

Answer 15

c is just +3

Answer 16

ohh, i forgot to do the discriminant

Answer 17

it is? why

Answer 18

ohh i get it

Answer 19

wait but i got a negative discriminant which means there are no real solutions...

Answer 20

how did u get a positive one

Answer 21

for this, there are actually no real solutions,
thats why there is "i" in the answers
which is imaginary number

Answer 22

so, what you got for b^2-4ac ?

Answer 23

ohh

Answer 24

i got -98

Answer 25

and negative means two imaginary solutions

Answer 26

try again ?

Answer 27

i did it wrong? ok

Answer 28

25 -4*3*9 = ... ?

Answer 29

ohhh i see my mistake hold on

Answer 30

wait ... its 567

Answer 31

nopes, ist -83

Answer 32

ugh i didnt do order of operations

Answer 33

ok lets keep going

Answer 34

so, you know
\(i =\sqrt {-1}\)
?

Answer 35

yeah

Answer 36

oh so now we can look at the choices

Answer 37

so, what about \(\sqrt{-83}\) ?
yes...

Answer 38

so sqrt -1 times -83

Answer 39

or is it 83

Answer 40

i think its b

Answer 41

bcuz the rest have a positive 5

Answer 42

and for the b value it is negative 5

Answer 43

-b means - (-5) = 5
so the answer should have +5

Answer 44

??

Answer 45

but before we said it was negative

Answer 46

can u like write it out??

Answer 47

where did the negative sign before the (-5) come from

Answer 48

yes

Answer 49

\(\huge{x_{1,2}=\frac{-b \pm \sqrt{b^2-4ac}}{2a}} \\ a=9, b=-5,c =3 \\ \huge{x_{1,2}=\frac{-(-5) \pm i\sqrt{83}}{2*9}}=...?\)

Answer 50

but why -(-5)?

Answer 51

OHHH

Answer 52

im so stupid :((

Answer 53

so i sqrt 83 will be -1 times 83 right

Answer 54

yes

Answer 55

ok

Answer 56

will 83 be under a sq rt