SOLUTION: how to find the zero 2x^2-x-1

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Question 1076197: how to find the zero 2x^2-x-1
Found 3 solutions by MathLover1, ikleyn, MathTherapy:
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

to find the zero 2x%5E2-x-1, first set it equal to zero
2x%5E2-x-1=0.....you can use quadratic formula
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ ....in your case a=2, b=-1, and c=-1
x+=+%28-%28-1%29+%2B-+sqrt%28+%28-1%29%5E2-4%2A2%2A%28-1%29+%29%29%2F%282%2A2%29+
x+=+%281+%2B-+sqrt%28+1%2B8+%29%29%2F4+

x+=+%281+%2B-+sqrt%28+9+%29%29%2F4+

x+=+%281+%2B-+3%29%2F4+
solutions:
x+=+%281+%2B+3%29%2F4+ =>x+=+4%2F4+ =>x+=+1
or
x+=+%281+-3%29%2F4+ =>x+=+-2%2F4+ =>x+=+-1%2F2



Answer by ikleyn(52909) About Me  (Show Source):
You can put this solution on YOUR website!
.
There is a bunch of lessons on solving quadratic equations in this site:
    - Introduction into Quadratic Equations
    - PROOF of quadratic formula by completing the square
    - Solving quadratic equations without quadratic formula
    - Who is who in quadratic equations
    - Using quadratic equations to solve word problems

Also, you have this free of charge online textbook in ALGEBRA-I in this site
    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this textbook under the topic "Quadratic equations".


Answer by MathTherapy(10557) About Me  (Show Source):
You can put this solution on YOUR website!

how to find the zero 2x^2-x-1
This should be in the form of an equation, as follows: y+=+2x%5E2+-+x+-+1

2x%5E2+-+x+-+1+=+0 --------- Substituting 0 for y

%282x+%2B+1%29%28x+-+1%29+=+0 ----- Factoring TRINOMIAL on left

2x + 1 = 0       OR      x - 1 = 0

2x = - 1         OR      x = 0 + 1

highlight_green%28matrix%281%2C7%2C+x%2C+%22=%22%2C+-+1%2F2%2C+or%2C+x%2C+%22=%22%2C+1%29%29

This is the SIMPLEST and best method, if you're familiar with it.