Question

Use the quadratic formula to solve the equation
-2x^2+9x+3=0

a. 9+sqrt105/4
b. 9+sqrt52/2
c. 9+sqrt105/2
d. 4+sqrt210/18 <--- am i right

Answer 1

No, that's not correct. What did you use as your values of a, b, and c?

Answer 2

a=2
b=9
c=3

Answer 3

In the problem statement you wrote that a = -2. So I found the values for a = -2.

Answer 4

ok..

Answer 5

yea it is -2

Answer 6

@mathteacher1729

Answer 7

Ok, so you'll have to re-do your work and check again, this time let a = -2. :)

Answer 8

I have to get dinner now, good luck, I will try to sign on later to check in.

Answer 9

k thanks

Answer 10

\(\bf \textit{quadratic formula}\\
{\color{blue}{ -2}}x^2{\color{red}{ +9}}x{\color{green}{ +3}}=0
\qquad \qquad
x= \cfrac{ - {\color{red}{ b}} \pm \sqrt { {\color{red}{ b}}^2 -4{\color{blue}{ a}}{\color{green}{ c}}}}{2{\color{blue}{ a}}}\)

solve for "x"

Answer 11

yea i did that and i got 19 for the denominator

Answer 12

i mean 18 sorry

Answer 13

and the numerator 81-24=57

Answer 14

hmmm

Answer 15

19 for the denominator?

Answer 16

how.. did you get 19 anyway for the denominator?

Answer 17

i meant 18

Answer 18

well.. what's "a"?

Answer 19

-2

Answer 20

so... "2a" would be?

Answer 21

oh i wasnt thinking. i thought the denominator was 2b my bad

Answer 22

2X-2=-4

Answer 23

yeap

thus \(\bf \textit{quadratic formula}\\
{\color{blue}{ -2}}x^2{\color{red}{ +9}}x{\color{green}{ +3}}=0
\qquad \qquad
x= \cfrac{ - {\color{red}{ b}} \pm \sqrt { {\color{red}{ b}}^2 -4{\color{blue}{ a}}{\color{green}{ c}}}}{2{\color{blue}{ a}}}
\\ \quad \\
x= \cfrac{ - {\color{red}{ 9}} \pm \sqrt { {\color{red}{ 9}}^2 -4{\color{blue}{ (-2)}}{\color{green}{ (3)}}}}{2{\color{blue}{ (-2)}}}\implies x=\cfrac{-9\pm\sqrt{81+24}}{-4}\)

Answer 24

so... what would you end up in the numerator?

Answer 25

ok the answer is a

Answer 26

dunno... what did you get on the numerator?

Answer 27

105 as the sqrt

Answer 28

yeap
thus \(\bf x= \cfrac{ - {\color{red}{ 9}} \pm \sqrt { {\color{red}{ 9}}^2 -4{\color{blue}{ (-2)}}{\color{green}{ (3)}}}}{2{\color{blue}{ (-2)}}}\implies x=\cfrac{-9\pm\sqrt{81+24}}{-4}
\\ \quad \\
x=\cfrac{-9\pm\sqrt{105}}{-4}\implies x=\cfrac{9\mp\sqrt{105}}{4}
\)

Answer 29

thanks

Answer 30

yw