SOLUTION: solve and check: 0=x^2-2x-1

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Question 110077: solve and check:
0=x^2-2x-1

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

solve:
0=x%5E2-2x-1..........cannot be factored
solve using quadratic formula:
x%5B1%2C2%5D=%28-b+%2B-+sqrt+%28b%5E2+-4%2Aa%2Ac+%29%29+%2F+%282%2Aa%29

x%5B1%2C2%5D=%28-%28-2%29+%2B-+sqrt+%28%28-2%29%5E2+-4%2A1%2A%28-1%29+%29%29+%2F+%282%2A1%29

x%5B1%2C2%5D=%282+%2B-+sqrt+%284+%2B+4+%29%29+%2F+2
x%5B1%2C2%5D=%282+%2B-+sqrt+%288%29%29+%2F+2
x%5B1%2C2%5D=%282+%2B-+2.83%29+%2F+2

x%5B1%5D=%282+%2B+2.83%29+%2F+2
x%5B1%5D=4.83+%2F+2
x%5B1%5D=%282.42%29+

x%5B2%5D=%282+-+2.83%29+%2F+2
x%5B2%5D=+-.83+%2F+2
x%5B2%5D=+-.42+%2F+2


check:
if x=+2.42,then
0=x%5E2-2x-1+=%282.42%29%5E2-2%2A%282.42%29-1+=+5.8564+-+4.84+-+1=+1.01+-+1+=+0+..

if x=+.+42,then
0=%28-.42%29%5E2+-+2%2A%28-.42%29-1+=+0.1764+%2B+.84+-+1=++1.01+-+1+=+0..