need help x2-2x-8=0?

Answer 1

x = 4 , -2

sam ;)

Answer 2

If you had noticed, the other two algebraic equations that i have solved for you, I have been using the two methods to prove to you that there are more ways than one to solve a question..

Nevertheless.. for this question...

p/s: pls do try to learn something out of all this...

x^2 - 2x - 8 = 0

The solution is as follows...

(x - 4) (x + 2) = 0

x = 4 or x = -2

Solution above is derived using the cross factorization method...

x -4 | -4x
x +2 | +2x
----------------
x^2 -8 | -2x


>>>Another way of solving this equation is by making use of the formula...
x = (-b +- sqrt(b^2-4ac))/2a...

In this case, a = 1, b = -2 and c = -8

thus...

x = [-(-2) + sqrt((-2)^2 - 4(1)(-8))]/2(1)
=[2 + sqrt(36)]/2
= 8/2 = 4

Or

x = [-(-2) - sqrt((-2)^2 - 4(1)(-8))]/2(1)
=[2 - sqrt(36)]/2
= -4/2 = -2

Hence, as you can see... either way you do it, you will still get the right and same answer...


Cheers... (",)

Answer 3

Isn't this your home work na?
You are studying at year 10 na?

k...
Answer is

x^2 - 2.X-8 = 0
X^2 - 4.x + 2.x -8 = 0
x(x-4) + 2(x-4) = 0
(x-4)(x+2) = 0

this can only happen when either (x-4) or (x2) or both become zeros.

(x-4) = 0 or (x+2) = 0

thanks...

so x = 4 or x = -2

Answer 4

It's not too hard to factor a quadratic that starts with x^2

Each factor has to have an x in it and the other numbers have to have a product of -8 and a sum of -2.

So, you can factor it like this: (x + 2)(x - 4)= 0

Setting each factor equal to zero and solving for x gives

x = -2 or x = 4

Answer 5

x^2 - 2x - 8 = 0
(x - 4)(x + 2) = 0
x = 4 or -2

Answer 6

x2-2x-8=0
x2-4x+2x-8=0
x(x-4)+2(x-4)
implies x=4,2

Answer 7

no