Question

Teach me how to solve this

3x^2-2x=8

Answer 1

how to put fraction inside of square root?

Answer 2

3x^2-6x+4x-8=0
3x(x-2)+4(x-2)=0
(3x+4)(x-2)=0
x=-4/3,2

Answer 3

3x^2-2x=8
9xsquared-2x=8
-8 -8
(3x-4)(3x+2)=0
x=-4/3,2

Answer 4

lol

Answer 5

@CUTE_AKKI Quadratic formula, if you will :)
@BoomShakalaka163 messaged me to use that method specifically

Answer 6

Very well then, @BoomShakalaka163
Show your progress.

Answer 7

how can i put fraction inside of square root?

Answer 8

using LaTeX?

Answer 9

just draw it if it's easier for you :)

Answer 10

3x^-2x=8 ~> 3x^2-2x-8=0

a=3 b=2=c8

x=-(2)\[\frac{ -2 \pm \sqrt{(-2^{2})}-4(3)(8) }{ 2(3) }\]

\[\frac{ 2 \pm \sqrt{4-96} }{6 }\]

\[\frac{ 2+92 }{6 }\]

but i dont think 94 is divisible by 6

Answer 11

c = -8 just sayin'

Answer 12

yes i transpose it 3x^-2x=8 ~> 3x^2-2x-8=0

Answer 13

Yes... that's why c = -8
but you used c = 8

Answer 14

oh yes, typo sorry. can you help me finish this.

Answer 15

Yeah... redo your solution, but use c = -8, and show me what happens.

Answer 16

it will be just -96

Answer 17

and since there was a minus sign, it will become + 96, correct?

Answer 18

so it will be 4+96?

Answer 19

yup :)

Answer 20

So it becomes...
\[\Large \frac{2+\pm \sqrt{4+96}}{4}\]

Answer 21

why 4? 2(3) is 6 am i right

Answer 22

typo :)
Sorry... replace with 6 :)

Answer 23

so x1 2+100/6=102/6 =17
and x2 2-100/6 = 98/6 = ? its invalid

Answer 24

don't forget that 4+96 was under a square-root sign...

Answer 25

it will become 25. 2+100/25 = 5 2-100/25= ..

Answer 26

\[\Large \frac{2+\pm \color{red}{\sqrt{4+96}}}{6}=\frac{2\pm \sqrt{100}}{6}\]
from here...?

Answer 27

doesnt it get removed after it was added? the sqt.

Answer 28

Square root of 100, lol, what is it?

Answer 29

10

Answer 30

Okay, so it becomes...
\[\Large \frac{2\pm10}{6}\]

Answer 31

but still if 2+10/6 =12/6=2
2-10/6 =8/6 =??

Answer 32

it's not 8/6 but -8/6
And it's equal to -4/3, simplified, which, if you notice, is one of the (correct) answers of
@CUTE_AKKI

Answer 33

ok so x1 = 2
x2 = -4/3?

Answer 34

am i correct with this guys?

x^2+8x-9 = 0
(x+9)(x-1)=0
x+9=0 x-1=0
x=9 x=-1

Answer 35

Nope...
It's almost correct... but
if
(x+9) = 0
doesn't that mean x = -9
and not x = 9?
think about it :)

Answer 36

i used quadratic equation by factoring

Answer 37

Yeah... and you factored well, it's the step that followed that was faulty.

Answer 38

btw im stuck at something let me show you.
8x^2+14x=-5
8x+14x+5=0
(2x+1)(4x+5)
2x+1=0 4x+5=0
x=2+1? x=4+5?

Answer 39

ok then x =-9 x=1 too.

Answer 40

\[2x+1 = 0\]\[2x = -1\]\[x = -\frac12\]nice and easy :)

Answer 41

4x+5=0
4x=-5
x=5/4

Answer 42

Don't be careless with signs.
It's -5/4

Answer 43

are you a student also?

Answer 44

Yup :)

Answer 45

you helped me almost everyday, but i always change in different usernames. lol

Answer 46

Who goes there?

Answer 47

yesterday i was little help same as the other day. i cant verify my email thats why

Answer 48

Well... just here playing around.. :P

Answer 49

so can you help me with my last question its about completing the square
x^2-3x-4=0?

Answer 50

Factor.

Answer 51

oh... I really should learn to read... sorry... hang on.

Answer 52

(x-4)(x+1)

Answer 53

i think its not the correct step

Answer 54

Yeah, that's not necessary,but since you already did it, I guess you already know the answers?

Answer 55

this was the given example

\[x-12=4x \]
\[x^2-4x=12\]
\[x^2-4x+4=12+4\]\[\sqrt{(x-2)^2=16}\]\[x-2=\pm4\]
x1=4+2=6
x2=-4+x=-2

Answer 56

Yes, I know how to complete the square (thank goodness) but since you already factored it into
(x-4)(x+1) = 0
you already know the answers?

I'm just doing this so that you know that we can also get to the correct answer using completing the square.

Answer 57

nope not yet.

Answer 58

Well, much like earlier when you solved by factoring... remember when you ahd
(x+9)(x-1)=0
the solutions were
x = -9
and
x = 1 ?
Same thing basically.

Answer 59

btw am i right on this

7x^2+19x=6
7x^2+19x-6=0
(7x-3)(x+2)
7x-3=0 x+2=0

x=3/7 x=-2

Answer 60

Yes.

Answer 61

i dont get the x2−4x+4=12+4

Answer 62

Okay... standard form for "completing the square" is this...
\[\LARGE x^2 +\color{red}bx = \color{green}c\]

Answer 63

Catch me so far?

Answer 64

so x^2-3x-4=0
x^2-3x=4
x^2 and then im lost

Answer 65

Yeah... relax...deep breaths... just look at that general form I gave you...

Answer 66

Now, the first step is to consider b... the number next to the x (with no exponent...)
In this case
x^2 - 3x - 4
What is b?

Answer 67

b is 3

Answer 68

Okay, so what I want you to do with it... is to take half of it... what's half of 3?

Answer 69

1.5

Answer 70

yes. or 3/2
I think you should use 3/2...
Now, square that number, you get?

Answer 71

x^2-3x+3=4+3?

Answer 72

Not 3... I said square the number, not double it... there's a difference :P

Answer 73

\[\sqrt{\left( x-3^2\right) =7}\]

Answer 74

You're getting WAY ahead of yourself, and you're doing it wrong...

Answer 75

x^2 - 3x +3^2- 4

Answer 76

No... it's not 3 you square, but 3/2.

Answer 77

i cant seem to understand

Answer 78

Okay... example...
x² - 6x - 16 = 0
x² - 6x = 16

Get half of 6, which is 3, and then square it... getting 9.
Add that to both sides...
x² - 6x + 9 = 16 + 9
(x - 3)² = 25
Get the square root of both sides
x - 3 = +- 5
x = 3 +- 5
x = 8 or -2

Answer 79

i now know the steps but i dont know what to do in 3/2

Answer 80

square it... you get 9/4 :)

Answer 81

and add that to both sides, giving you...
\[\Large x^2 -3x + \frac94 = 4 + \frac94\]
\[\Large\left( x- \frac32\right)^2 = \frac{25}4\]
solve from here.

Answer 82

x-3/2^2=25/4
x-3/2=+-5/2
x-3/2=5/2
x1=5/2+3/2=8/4 =4/2 = 2
x2=-5/2+3/2 = 2/2 = 1 am i correct?

Answer 83

How come 5/2 + 3/2 becomes 8/4
Did you add denominators?
As for
-5/2 + 3/2 = 2/2
I told you once, I told you a thousand times... PAY ATTENTION TO SIGNS.

Answer 84

yes i did add.

Answer 85

sorry, i get very forgetful.

Answer 86

You don't add denominators. Big No-no

Answer 87

oh, sorry so its 8/2 = 4
-2/2 = 1

Answer 88

Seriously o.O
Watch the signs...

Answer 89

Or else review multiplication and division of integers.

Answer 90

i will do that so am i right?
8/2 = 4
-2/2 = -1

Answer 91

Okay, better.

Answer 92

thanks again for clearing me that terrenz.
but im still lost at the quadratic formula.
x1=2 x2=-4/3?

Answer 93

Yes, those are the answers.

Answer 94

ok thanks, ill try to review it now and clear it more enough lol, btw is the factor of
4x^2-36= (4x-4)(x-9)?

Answer 95

No.

Answer 96

4(x+3)(x-3)?

Answer 97

That's better.