help!

I need to solve 2x^2-x-1=0

You can use the quadratic formula. This formula can factor any trinomial. It is as follows:

[CENTER]-b+or-sqrt(b^2-4ac)
2a =x

The reason there is a plus or minus is because there are usually 2 answers to a trinomial.

a is the number the squared variable is multiplied by, in this case 2. (2x^2)
b is the number the variable is multiplied by, in this case -1. (-x)
c is the number the number with no variable is, in this case -1. (-1)

Now, all you have to do is find the answers to the equation:

1+or-sqrt[(-1)^2-4(2)(-1)]
2a =x

Sorry if you already know what the quadratic formula is but I can only assume that it is completely new to you.

Sorry, the underlined part is supposed to be all divided by the 2a and that quotient will be x.

Also, In the second equation 2a should be 2(2).

Well, it's a perfect square... by inspection, we know that:

2x^2 - x - 1 = (2x+1)(x-1)

I don't find any serious need to use the quadratic formula, which is more time consuming... and if it's difficult to understand the formula, let me post it:

For a quadratic equation of the form:

ax^2 + bx + c = 0

The formula for solving x is:

x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}