Solve r^(2)-2r-1 - ScanMath

Evaluate

r^{2} - 2 r - 1

To find the roots of the expression,set the expression equal to 0

r^{2} - 2 r - 1 = 0

Substitute a= 1,b= - 2 and c= - 1 into the quadratic formula r = \frac{- b \pm b ^{2} - 4 a c}{2 a}

r = \frac{2 \pm ( - 2 ) ^{2} - 4 ( - 1 )}{2}

Simplify the expression

More Steps

r = \frac{2 \pm 8}{2}

Simplify the radical expression

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r = \frac{2 \pm 2 2}{2}

Separate the equation into 2 possible cases

r = \frac{2 + 2 2}{2} r = \frac{2 - 2 2}{2}

Simplify the expression

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r = 1 + 2 r = \frac{2 - 2 2}{2}

Simplify the expression

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r = 1 + 2 r = 1 - 2

Solution

r_{1} = 1 - 2, r_{2} = 1 + 2

Alternative Form

r_{1} \approx - 0.414214, r_{2} \approx 2.414214

Find the roots