Question

Solve x2 + 8x = -3

Answer 1

Do you know how to complete the square?

Answer 2

no not really

Answer 3

well \(x^2+bx=c\implies (x+\frac{b}{2})^2=c+(\frac{b}{2})^2\)

Answer 4

so for you

\((x+4)^2=-3+4^2=13\)

Answer 5

howd you get the 4

Answer 6

So you have \((x+4)^2=13\)

Answer 7

well \(x^2+bx=c\) what is \(b\) in your case?

Answer 8

2

Answer 9

\(\huge x^2+bx=c\)
\(\huge x^2+8x=-3\)

compare these two equations, what is in the b position in the second equation

Answer 10

8

Answer 11

so what is b/2?

Answer 12

4

Answer 13

what is c?

Answer 14

13

Answer 15

look back up to where I said compare the equations

Answer 16

what is c?

Answer 17

-3

Answer 18

right

Answer 19

ok now

Answer 20

ok using this
\(x^2+\color{blue}{b}x=\color{red}{c}\implies (x+\frac{\color{blue}{b}}{2})^2=\color{red}{c}+(\frac{\color{blue}{b}}{2})^2\)
and the fact that
\(\color{blue}{b=8}\) and \(\color{red}{c=-3}\)

we get \((x+\frac{\color{blue}{8}}{2})^2=-3+(\frac{\color{blue}{8}}{2})^2\)

Answer 21

you with me?

Answer 22

then you you simplify

Answer 23

correct, then you will get

\((x+4)^2=13\)

Answer 24

now square both sides

\(x+4=\pm\sqrt{13}\iff x=-4\pm\sqrt{13}\)

Answer 25

\[-4\pm \sqrt{{13}}\]

Answer 26

?

Answer 27

what is your question

Answer 28

is that the answer^

Answer 29

and i have another question .. about a test

Answer 30

yes

Answer 31

ive got a final coming up this week thats worth 275(20%) ...it has 36 multiple choice and 4 free response.. i have to get a 60% on the final or i dont get credit for the class. how many questions do you think i would have to get right to get a 60%

Answer 32

@zzr0ck3r

Answer 33

thats worth 20% of what?

Answer 34

close this and open a new question