Question

Solve: x^2 − 2x − 24 = 0.

x = 4, x = 6

x = 4, x = −6

x = −4, x = 6

x = −4, x = −6

Answer 1

Do you know these methods? if any:
Completing the square.
Quadratic formula
factoring.

Answer 2

\[\begin{array}{*{20}c} {x = \frac{{ - b \pm \sqrt {b^2 - 4ac} }}{{2a}}} & {{\rm{when}}} & {ax^2 + bx + c = 0} \\ \end{array} \]

Use the quadratic formula

Answer 3

So I would use ax^2 + bx + c

Answer 4

It's always a sure way to find the answer if you don't know how to do it any other method.

Answer 5

yes
for example
a=1

Answer 6

Can you tell me what are a, b and c? Let's do it with quadratic formula.

Answer 7

a = 1, b = 2 and c = 24

Answer 8

you forgot the negative signs.

Answer 9

find the factors of -24 that add to -2.... the hint is the larger factor is negative

Answer 10

Hmm. It's actually a = 1, b = -2, c = -24

Answer 11

not if it's -b * -2

Answer 12

It converts to a positive

Answer 13

How do we have a positive here?

Answer 14

Nevermind. I'm thinking of something else.

Answer 15

a = 1 b = -2 and c = -24.

Answer 16

Yes.

Answer 17

Now what?

Answer 18

Now plug that into the formula.

Answer 19

How?

Answer 20

OH

Answer 21

factors of - 24 -24 + 1 = -23
-12 + 2 = -10
- 8 + 3 = -5
-6 + 4 = -2

woohooo its -6 and 4

then 0 = (x - 6)(x+4)

so the is x = -4, 6

Answer 22

1x^2 - 2x - 24

Answer 23

\( \color{Black}{\Rightarrow \Large {-(-2) \pm\sqrt{(-2)^2 + 4(1)(-24)} \over 2(1)} }\)

Answer 24

I don't get it.

Answer 25

Can you do it now?

Answer 26

why those numbers ... well its because

use substitutions

0 = (6 - 6)(6 + 4) or 0 = (-4-6)(-4 +4)
= (0) (10) = (-10)(0)
= 0 = 0

wow it works

Answer 27

\( \color{Black}{\Rightarrow\Large {2 \pm \sqrt{4 - 96} \over 2}}\)

Answer 28

\( \color{Black}{\Rightarrow x = \Large{2 \pm \sqrt{-92} \over 2} }\)

Answer 29

When you use those things it confuses me.

Answer 30

Well anyway my first choice would be factoring.

Answer 31

If you're not able to factor, then I reckon you the formula.

Answer 32

Factor each number?

Answer 33

Formula confuses everyone :P

Answer 34

See what @campbell_st said.

Answer 35

it should be b^2 - 4ac not b^2 + 4ac

Answer 36

PARTH... you have a hugh error i n the discriminant.... it should be 4 + 96 4 x 1 x -24 = 96

Answer 37

both ways work

Answer 38

Yeah, that's what I was thinking

Answer 39

I see. Could I do it? No. But do I get this problem, sure.
I don't know. It takes me 30 min. to an hour for each problem. It sucks.. truly sucks.

Answer 40

Do you guys mind if I help him out for a minute?

Answer 41

careless... work on factors... if its not obvious go to the general quadratic formula

Answer 42

What do you mean factors

Answer 43

Whats the next one?

Answer 44

\( \color{Black}{\Rightarrow x = \Large{-(-2)\pm\sqrt{100} \over 2}}\)

\( \color{Black}{\Rightarrow x = \Large{2 \pm 10 \over 2} }\)

\( \color{Black}{\Rightarrow x = 6 \textbf{ or} -4 }\)

Answer 45

Solve: 0 = 6x2 − 10x − 4.

Answer 46

This time do factorisation :P

Answer 47

Solve: 0 = 6x^2 − 10x − 4.

Answer 48

No, @ Parth

Answer 49

\( \color{Black}{\Rightarrow 6x^2 - 12x + 2x - 4 = 0 }\)

Sorry....uh

Answer 50

What you do is first you express \(bx\) as a sum of two numbers \(\alpha x\) and \(\beta x\) such that \(\alpha \times \beta = ac\)

Answer 51

And, then, you group the first two and last two terms.

Answer 52

... I don't get it man.

Answer 53

\( \color{Black}{\Rightarrow 6x(x - 2) + 2(x - 2) = 0 }\)
\( \color{Black}{\Rightarrow (6x + 2)(x - 2) = 0 }\)

Using the zero product theorem, either 6x + 2 = 0, or x - 2 = 0

Answer 54

Or wait, you may factor further.

\( \color{Black}{\Rightarrow 2(3x + 1)(x - 2) = 0 }\)

Answer 55

here is a solution to it take 2 out as a common factor

2(3x^2 - 5x - 2) = 0

multiply 3 by -2 a x c 3 x -2 = -6 factors of -6 that give b are -6 + 1

then its




take out any common factors