Question

Medal!
Solve 2x^2 - 8x = -7

Answer 1

DO you recall the quadratic formula thing

Answer 2

Umm, i recall it i just don't remember it...

Answer 3

for Ax^2 + Bx + C = 0
\[x = \frac{ -B +- \sqrt{B^2 - 4* A *C} }{ 2A }\]

Answer 4

here, you have

2x^2 - 8X + 7 = 0

A = 2
B= -8
C = 7

Answer 5

Yes. So now just plug it in and solve for that?

Answer 6

right

Answer 7

x = 8 +-√-8^2 - 4 * 2 * 7 / 2(2)

Answer 8

well then it doesn't like my square root sign, thats what the question marks are

Answer 9

reload page

Answer 10

So, then i would start by simplifying the 2(2) and everything inside the square root right?

Answer 11

right so you get
\[x = \frac{ 8 +- \sqrt{(-8)^2- 4 * 2 * 7} }{ 2(-8) }\]

Answer 12

\[x = \frac{ 8 +- \sqrt{8} }{ -16 }\]

Answer 13

Are you sure for the denominator? because A is 2

Answer 14

Yes you are right, my mistake. lol

Answer 15

\[\sqrt{8} = \sqrt{2*4} = 2\sqrt{2}\]

Answer 16

\[\frac{ 8 +-2\sqrt{2} }{ 4 }\]

Answer 17

divide each tem by 2

Answer 18

\[\frac{ 4 +- \sqrt{2} }{ 2 }\]

Answer 19

ok..

Answer 20

\[x = \frac{ 4 + \sqrt{2} }{ 2 } \]
or
\[x = \frac{ 4 - \sqrt{2} }{ 2 }\]

Answer 21

Thats it, unless you use a calculator to get a decimal number for both of em

Answer 22

negative 2 plus or minus square root of 2
negative 2 plus or minus 2 square root of 2
quantity of 2 plus or minus square root of 2 all over 2
2 plus or minus square root of 2 end root over 2

are my options

Answer 23

Right, if you divide the 2 into both of em you get

\[2 +or- \frac{ \sqrt{2} }{ 2 }\]

Answer 24

so the third one

Answer 25

OK! thanks! and could you explain how you simplified inside the square root for me?

Answer 26

wait, not third

Answer 27

√(−8)^2−4∗2∗7

Answer 28

the fourth one

Answer 29

@DanJS thanks for the help but could you tell me how you simplified inside of the square root?

Answer 30

@DanJS ?

Answer 31

sure

Answer 32

\[\sqrt{(-8)^2 - 4 * 2 *7}\]

Answer 33

if you are squaring a negative number, remember it is
(-8)(-8) = +64
not
-(8)(8) = -64

The parenthesis go around the negative sign too

Answer 34

\[\sqrt{64 - 56}\]

Answer 35

\[\sqrt{8}\]

Answer 36

\[\sqrt{2 * 4} = \sqrt{ 2}\sqrt{4} = 2*\sqrt{2}\]

Answer 37

This helps so much thanks!

Answer 38

so square root of 8 = 2*square root of 2

Answer 39

no prob, yw

Answer 40

@DanJS Ok, so on my next problem, it ends up with a square root of 29 once i simplify it from long form, so how would i do that into something like 4 * 2?

Answer 41

you cant, 29 is a prime number, root 29 is the most you can simplify it

Answer 42

ok