Question

Use the quadratic formula to solve the equation.
x^2-2x= 99

Answer 1

@satellite73

Answer 2

You still there for me to answer?

Answer 3

Yes

Answer 4

Ok. So you will get x^2 - 2x - 99 = 0

Answer 5

\[x^2-2x= 99 \\
(x-1)^2=99+1=100\\
x-1=10,x-1=-10\\
x=11,x=-9\]

Answer 6

@satellite73 That is not solving using the quadratic formula.

Answer 7

It has to be quadratic formula.

Answer 8

You use the coefficient of X^2 - 2x - 99 = 0 in order to find the coefficients and thus determine a, b and c.

Answer 9

So, a = 1, b = -2 and c = -99

Answer 10

A= 1 B= -2 C= -99

Answer 11

I get 20 as the discriminant

Answer 12

\[(-b \pm \sqrt{b ^{2}-4ac})\div2a\]

Answer 13

So you plug the numbers given above into the quadratic formula to come up with 2 solutions.

Answer 14

I don't get 11 and -9

Answer 15

Don't think that is what you're meant to get. I'll try it.

Answer 16

The answer is -9 and 11. I just don't know how to get it.

Answer 17

Is it possible that this includes an imaginary number?

Answer 18

Oh no never mind.

Answer 19

Yes I got the correct result using the quadratic formula.

Answer 20

Don't forget that subtracting a negative makes it a positive.

Answer 21

Can you show me :x

Answer 22

\[\frac{ 2\pm \sqrt{4-(4-99)} }{ 2 }\]

Answer 23

\[\frac{ 2\pm \sqrt{400} }{ 2 }\]

Answer 24

\[\frac{ 2\pm20 }{ 2 }\]

Answer 25

\[1\pm10\]

Answer 26

So 1 + 10 = 11 and 1 - 10 = -9.

Answer 27

I'm confused on how you got 4-(4-99)

Answer 28

Sorry. That was meant to be 4*-99. And the 4 you get by doing b^2, so -2^2.