How would you solve this (It's on calculator paper): x² - 2x - 1 = 0

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I am seriously confused; you can't exactly use the quadratic equation for this, can you? :s

Posted Fri 3rd June, 2011 @ 20:29 by Nemo'

6 Answers

  • 1 vote

i would use the quadratic formula.. and the answer would probably be x= 2.414... or x= -0.414...

Answered Sat 4th June, 2011 @ 00:13 by Christine
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just try it and see if you get answers that make sense. Always use the quadratic formula if you can't find any numbers to sub in :) x

Answered Fri 3rd June, 2011 @ 20:45 by Kelly:)
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I really cant think of a the 2 numbers to break this into product and sum, so it will probably have to be the quadratic formula :s what does the mark scheme say? sometimes its better to work backwards from the answer

Answered Fri 3rd June, 2011 @ 22:10 by Lamise Hassan
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does the question say what accuracy to give it to eg. 2 decimal places

if it does use the quadratic equation formula

in a calculator exam, it is always possible to check your answer using the formula

Answered Sat 4th June, 2011 @ 13:06 by Pui Pui
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Use the formula, think about what a, b and c equal (in this one a=1, b=-2 and c=-1) and just substitute the numbers in.

Answered Sat 4th June, 2011 @ 13:29 by Sarah
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I'm sorry to say that you can't use the quadratic formula for that. Substituting a, b and c is just not a viable option.

Answered Sun 5th June, 2011 @ 00:20 by Maleficent