x^2-x-1=0 quadractic formula?

Question

I still don't get it maybe this will be simpler

not homework trying to teach myself algebra and I have been out of school for 5 years. any help would be appreciated

Answer 1

X= -b plus or minus the square root of (b)^2 – 4 (a)(c), all over 2(a)

Just substitute them into the equation: a= 1 because 1x^2 is 1 (always use the number in front of the x^2 for a).
b= -1 because -1x (always use the number in front of x for b)
c= -1 because -1 is the number that stands alone (always use this for c)

Now just substitute the numbers into the equation and solve it, the answer should come out to be: 1 plus or minus the square root of 5 over 2

Good luck!

REMEMBER: a negative times a negative makes a positive so when u substitute -1 in for b at the beginning of the equations the –b should be –(-1) which makes a positive 1. The rule applies for all algebra.

Answer 2

You want to use the quadratic formula to solve it.

The equation is in the form ax^2 + bx + c = 0
and the quadratic equation is
[-b +or- root(b^2 - 4ac)] / 2a

First you must find what a,b and c are in your equation. Since there is only one X^2, a=1. There is a -1 in front of the x for your -x so b=-1. C = -1 obviously. Now all you have to do is plug a,b, and c into the quadratic equation.

[-(-1) +or- squareroot((-1)^2 -4(1)(-1))]/2(1)

Simplify

[1 +or- squareroot(5)] / 2

So your answer will be:

.5 + root(5)/2
or
.5 - root(5)/2

Answer 3

quadratic formula is x = -b + or - sqr(b^2 - 4ac)/2a

your equation x^2 - x - 1 = 0 is in the form of
ax^2 + bx + c = 0 with a and b = 1 because a variable without a coefficient the coefficient is assumed to be 1 and c is the lone integer, the =0 is to be ignored.

you just plug in your variables and solve for x twice

Answer 4

X^2-x-1=0
x=(1+/-√(1+4))/2
x=(1+√5)/2 (1-√5)/2

Answer 5

You can use the quadratic equation to solve this. It is: x = -b =/- [sqr(b^2-4ac)]/2a. In your problem then, a = 1, b = -1, and c -1. Plug these in and solve.

Answer 6

What don't you get?

1 ± Sq Root ( 5) ÷ 2 = 1.618 or -0.61803

Answer 7

what are you asking about? do you want to know if it is or what the answer is?

i think the answer is one plus or minus the square root of 5 all over two. i think.

Answer 8

isn't this YOUR homework? and isn't that the same exact polynomial that they use to explain the quadratic formula, except with subtractions instead of additions?

Answer 9

yes it is. quadratic means that there is an x^2 in the equation

Answer 10

hope the website helps